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solv-int/9909017 | Darboux transformations for a Bogoyavlenskii equation in 2+1 dimensions | P. G. Estevez and G. A. Hernaez (Universidad de Salamanca, Spain) | solv-int nlin.SI | https://arxiv.org/abs/solv-int/9909017 | 2016-11-23 | We use the singular manifold method to obtain the Lax pair, Darboux transformations and soliton solutions for a (2+1) dimensional integrable equation. |
solv-int/9909018 | Surfaces of Constant negative Scalar Curvature and the Correpondence between the Liouvulle and the sine-Gordon Equations | H. Belich, G. Cuba and R. Paunov | solv-int nlin.SI | https://arxiv.org/abs/solv-int/9909018 | 2007-05-23 | By studying the {\it internal} Riemannian geometry of the surfaces of constant negative scalar curvature, we obtain a natural map between the Liouville, and the sine-Gordon equations. First, considering isometric immersions into the Lobachevskian plane, we obtain an uniform expression for the general (locally defined) solution of both the equations. Second, we prove that there is a Lie-B\"acklund transformation interpolating between Liouville and sine-Gordon. Third, we use isometric immersions into the Lobachevskian plane to describe sine-Gordon N-solitons explicitly. |
solv-int/9909019 | The Structure of the Bazhanov-Baxter Model and a New Solution of the Tetrahedron Equation | M.Horibe and K.Shigemoto | solv-int nlin.SI | https://arxiv.org/abs/solv-int/9909019 | 2009-10-31 | We clarify the structure of the Bazhanov-Baxter model of the 3-dim N-state integrable model. There are two essential points, i) the cubic symmetries, and ii) the spherical trigonometry parametrization, to understand the structure of this model. We propose two approaches to find a candidate as a solution of the tetrahedron equation, and we find a new solution. |
solv-int/9909020 | The complex Toda chains and the simple Lie algebras - solutions and large time asymptotics -- II | V. S. Gerdjikov (Institute for Nuclear Research and Nuclear Energy, Bulg. Acad. of Sci., Sofia,Bulgaria), E. G. Evstatiev (Department of Physics, University of Texas at Austin, Austin, Texas, USA), R. I. Ivanov (Department of Mathematical Physics National University of Ireland - Galway, Galway, Ireland) | solv-int nlin.SI | https://arxiv.org/abs/solv-int/9909020 | 2024-09-06 | We propose a compact and explicit expression for the solutions of the complex Toda chains related to the classical series of simple Lie algebras g. The solutions are parametrized by a minimal set of scattering data for the corresponding Lax matrix. They are expressed as sums over the weight systems of the fundamental representations of g and are explicitly covariant under the corresponding Weyl group action. In deriving these results we start from the Moser formula for the A_r series and obtain the results for the other classical series of Lie algebras by imposing appropriate involutions on the scattering data. Thus we also show how Moser's solution goes into the one of Olshanetsky and Perelomov. The results for the large-time asymptotics of the A_r -CTC solutions are extended to the other classical series B_r - D_r. We exhibit also some `irregular' solutions for the D_{2n+1} algebras whose asymptotic regimes at t ->\pm\infty are qualitatively different. Interesting examples of bounded and periodic solutions are presented and the relations between the solutions for the algebras D_4, B_3 and G_2 $ are analyzed. |
solv-int/9909021 | Self-similar solutions of NLS-type dynamical systems | M. Boiti, V.G. Marikhin, F. Pempinelli, A.B. Shabat | solv-int nlin.SI | https://arxiv.org/abs/solv-int/9909021 | 2007-05-23 | We study self-similar solutions of NLS-type dynamical systems. Lagrangian approach is used to show that they can be reduced to three canonical forms, which are related by Miura transformations. The fourth Painleve equation (PIV) is central in our consideration - it connects Heisenberg model, Volterra model and Toda model to each other. The connection between the rational solutions of PIV and Coulomb gas in a parabolic potential is established. We discuss also the possibility to obtain an exact solution for optical soliton i.e. of the NLS equation with time-dependent dispersion. |
solv-int/9909022 | Self-similarity in Spectral Problems and q-special Functions | I.Loutsenko, V.Spiridonov | solv-int hep-th nlin.SI | https://arxiv.org/abs/solv-int/9909022 | 2007-05-23 | Similarity symmetries of the factorization chains for one-dimensional differential and finite-difference Schr\"odinger equations are discussed. Properties of the potentials defined by self-similar reductions of these chains are reviewed. In particular, their algebraic structure, relations to $q$-special functions, infinite soliton systems, supersymmetry, coherent states, orthogonal polynomials, one-dimensional Ising chains and random matrices are outlined. |
solv-int/9909023 | Orthogonal and symplectic matrix integrals and coupled KP hierarchy | Saburo Kakei | solv-int hep-th math-ph math.MP nlin.SI | https://arxiv.org/abs/solv-int/9909023 | 2009-10-31 | Orthogonal and symplectic matrix integrals are investigated. It is shown that the matrix integrals can be considered as a $\tau$-function of the coupled KP hierarchy, whose solution can be expressed in terms of pfaffians. |
solv-int/9909024 | Dressing method and the coupled KP hierarchy | Saburo Kakei | solv-int math-ph math.MP nlin.SI | https://arxiv.org/abs/solv-int/9909024 | 2009-10-31 | The coupled KP hierarchy, introduced by Hirota and Ohta, are investigated by using the dressing method. It is shown that the coupled KP hierarchy can be reformulated as a reduced case of the 2-component KP hierarchy. |
solv-int/9909025 | Quasi-Lagrangian Systems of Newton Equations | Stefan Rauch-Wojciechowski, Krzysztof Marciniak, Hans Lundmark | solv-int nlin.SI | https://arxiv.org/abs/solv-int/9909025 | 2009-10-31 | Systems of Newton equations of the form $\ddot{q}=-{1/2}A^{-1}(q)\nabla k$ with an integral of motion quadratic in velocities are studied. These equations generalize the potential case (when A=I, the identity matrix) and they admit a curious quasi-Lagrangian formulation which differs from the standard Lagrange equations by the plus sign between terms. A theory of such quasi-Lagrangian Newton (qLN) systems having two functionally independent integrals of motion is developed with focus on two-dimensional systems. Such systems admit a bi-Hamiltonian formulation and are proved to be completely integrable by embedding into five-dimensional integrable systems. They are characterized by a linear, second-order PDE which we call the fundamental equation. Fundamental equations are classified through linear pencils of matrices associated with qLN systems. The theory is illustrated by two classes of systems: separable potential systems and driven systems. New separation variables for driven systems are found. These variables are based on sets of non-confocal conics. An effective criterion for existence of a qLN formulation of a given system is formulated and applied to dynamical systems of the Henon-Heiles type. |
solv-int/9909026 | On a Schwarzian PDE associated with the KdV Hierarchy | Frank Nijhoff (University of Leeds), Andrew Hone and Nalini Joshi (University of Adelaide) | solv-int nlin.SI | https://arxiv.org/abs/solv-int/9909026 | 2009-10-31 | We present a novel integrable non-autonomous partial differential equation of the Schwarzian type, i.e. invariant under M\"obius transformations, that is related to the Korteweg-de Vries hierarchy. In fact, this PDE can be considered as the generating equation for the entire hierarchy of Schwarzian KdV equations. We present its Lax pair, establish its connection with the SKdV hierarchy, its Miura relations to similar generating PDEs for the modified and regular KdV hierarchies and its Lagrangian structure. Finally we demonstrate that its similarity reductions lead to the {\it full} Painlev\'e VI equation, i.e. with four arbitary parameters. |
solv-int/9909027 | On two aspects of the Painleve analysis | Sergei Sakovich | solv-int math-ph math.AP math.MP nlin.SI | https://arxiv.org/abs/solv-int/9909027 | 2013-03-28 | We use the Calogero equation to illustrate the following two aspects of the Painleve analysis of nonlinear PDEs. First, if a nonlinear equation passes the Painleve test for integrability, the singular expansions of its solutions around characteristic hypersurfaces can be neither single-valued functions of independent variables nor single-valued functionals of data. Second, if the truncation of singular expansions of solutions is consistent, the truncation not necessarily leads to the simplest, or elementary, auto-Backlund transformation related to the Lax pair. |
solv-int/9909028 | Matrix integrals and the geometry of spinors | Johan van de Leur | solv-int adap-org hep-th math-ph math.MP nlin.SI | https://arxiv.org/abs/solv-int/9909028 | 2016-09-08 | We obtain the collection of symmetric and symplectic matrix integrals and the collection of Pfaffian tau-functions, recently described by Peng and Adler and van Moerbeke, as specific elements in the Spin-group orbit of the vacuum vector of a fermionic Fock space. This fermionic Fock space is the same space as one constructs to obtain the KP and 1-Toda lattice hierarchy. |
solv-int/9910001 | Dispersionless Fermionic KdV | J. Barcelos-Neto, Alin Constandache and Ashok Das | solv-int hep-th nlin.SI | https://arxiv.org/abs/solv-int/9910001 | 2009-10-31 | We analyze the dispersionless limits of the Kupershmidt equation, the SUSY KdV-B equation and the SUSY KdV equation. We present the Lax description for each of these models and bring out various properties associated with them as well as discuss open questions that need to be addressed in connection with these models. |
solv-int/9910002 | The KdV equation on a half-line | I.T.Habibullin and A.N.Vil'danov | solv-int nlin.SI | https://arxiv.org/abs/solv-int/9910002 | 2007-05-23 | The initial boundary value problem on a half-line for the KdV equation with the boundary conditions $u|_{x=0}=a\leq0$, $u_{xx}|_{x=0}=3a^2$ is integrated by means of the inverse scattering method. In order to find the time evolution of the scattering matrix it turned out to be sufficient to solve the Riemann problem on a hyperelliptic curve of genus two, where the conjugation matrices are effectively defined by initial data. |
solv-int/9910003 | Yang-Baxter Algebra for the n-Harmonic Oscillator Realisation of sp(2n,R) | A.J. Macfarlane, F. Wagner | solv-int math-ph math.MP nlin.SI | https://arxiv.org/abs/solv-int/9910003 | 2016-09-08 | Using a rational R-matrix associated with the 4 x 4 defining matrix representation of c_2=sp(4), the Lie algebra of Sp(4), a one-site operator solution of the associated Yang-Baxter algebra acting in the Fock space of two harmonic oscillators is derived. This is used to define N-site integrable systems, which are soluble by a version of the algebraic Bethe ansatz method without nesting. All essential aspects of the work generalise directly from c_2 to c_n. |
solv-int/9910004 | On integrable discretization of the inhomogeneous Ablowitz-Ladik model | V. V. Konotop (U. of Lisbon) | solv-int nlin.SI | https://arxiv.org/abs/solv-int/9910004 | 2009-10-31 | An integrable discretization of the inhomogeneous Ablowitz-Ladik model with a linear force is introduced. Conditions on parameters of the discretization which are necessary for reproducing Bloch oscillations are obtained. In particular, it is shown that the step of the discretization must be comensurable with the period of oscillations imposed by the inhomogeneous force. By proper choice of the step of the discretization the period of oscillations of a soliton in the discrete model can be made equal to an integer number of periods of oscillations in the underline continuous-time lattice. |
solv-int/9910005 | Lax pair, Darboux Transformations and solitonic solutions for a (2+1) dimensional NLSE | P. G. Estevez and G.A. Hern\'aez (Universidad de Salamanca, SPAIN) | solv-int nlin.SI | https://arxiv.org/abs/solv-int/9910005 | 2007-05-23 | In this paper the Singular Manifold Method has allowed us to obtain the Lax pair, Darboux transformations and tau functions for a non-linear Schr\"odiger equation in 2+1 dimensions. In this way we can iteratively build different kind of solutions with solitonic behavior. |
solv-int/9910006 | Beyond Nonlinear Schr\"odinger Equation Approximation for an Anharmonic Chain with Harmonic Long Range Interaction | D. Grecu, Anca Visinescu, A. S. Carstea | solv-int nlin.SI | https://arxiv.org/abs/solv-int/9910006 | 2007-05-23 | Multi scales method is used to analyze a nonlinear differential-difference equation. In order $\epsilon^3$ the NLS equation is found to determine the space-time evolution of the leading amplitude. In the next order this has to satisfy a complex mKdV equation (the next in the NLS hierarchy) in order to eliminate secular terms. The zero dispersion point case is also analyzed and the relevant equation is a modified NLS equation with a third order derivative term included |
solv-int/9910007 | Singularity confinement and algebraic entropy: the case of the discrete Painlev\'e equations | Y. Ohta, K.M. Tamizhmani, B. Grammaticos and A. Ramani | solv-int nlin.SI | https://arxiv.org/abs/solv-int/9910007 | 2009-10-31 | We examine the validity of the results obtained with the singularity confinement integrability criterion in the case of discrete Painlev\'e equations. The method used is based on the requirement of non-exponential growth of the homogeneous degree of the iterate of the mapping. We show that when we start from an integrable autonomous mapping and deautonomise it using singularity confinement the degrees of growth of the nonautonomous mapping and of the autonomous one are identical. Thus this low-growth based approach is compatible with the integrability of the results obtained through singularity confinement. The origin of the singularity confinement property and its necessary character for integrability are also analysed. |
solv-int/9910008 | Exact Solution of the Quantum Calogero-Gaudin System and of its q-Deformation | F. Musso, O. Ragnisco | solv-int nlin.SI | https://arxiv.org/abs/solv-int/9910008 | 2015-06-26 | A complete set of commuting observables for the Calogero-Gaudin system is diagonalized, and the explicit form of the corresponding eigenvalues and eigenfunctions is derived. We use a purely algebraic procedure exploiting the co-algebra invariance of the model; with the proper technical modifications this procedure can be applied to the $q-$deformed version of the model, which is then also exactly solved. |
solv-int/9910009 | N=2 Hamiltonians with sl(2) coalgebra symmetry and their integrable deformations | A. Ballesteros, O. Ragnisco | solv-int nlin.SI | https://arxiv.org/abs/solv-int/9910009 | 2007-05-23 | Two dimensional classical integrable systems and different integrable deformations for them are derived from phase space realizations of classical $sl(2)$ Poisson coalgebras and their $q-$deformed analogues. Generalizations of Morse, oscillator and centrifugal potentials are obtained. The N=2 Calogero system is shown to be $sl(2)$ coalgebra invariant and the well-known Jordan-Schwinger realization can be also derived from a (non-coassociative) coproduct on $sl(2)$. The Gaudin Hamiltonian associated to such Jordan-Schwinger construction is presented. Through these examples, it can be clearly appreciated how the coalgebra symmetry of a hamiltonian system allows a straightforward construction of different integrable deformations for it. |
solv-int/9910010 | Schlesinger transformations for elliptic isomonodromic deformations | D. Korotkin, N. Manojlovic, H. Samtleben | solv-int hep-th nlin.SI | https://arxiv.org/abs/solv-int/9910010 | 2015-06-26 | Schlesinger transformations are discrete monodromy preserving symmetry transformations of the classical Schlesinger system. Generalizing well-known results from the Riemann sphere we construct these transformations for isomonodromic deformations on genus one Riemann surfaces. Their action on the system's tau-function is computed and we obtain an explicit expression for the ratio of the old and the transformed tau-function. |
solv-int/9910011 | The averaging of non-local Hamiltonian structures in Whitham's method | Andrei Ya. Maltsev | solv-int nlin.SI | https://arxiv.org/abs/solv-int/9910011 | 2017-07-28 | We consider the $m$-phase Whitham's averaging method and propose a procedure of "averaging" of non-local Hamiltonian structures. The procedure is based on the existence of a sufficient number of local commuting integrals of a system and gives a Poisson bracket of Ferapontov type for the Whitham's system. The method can be considered as a generalization of the Dubrovin-Novikov procedure for the local field-theoretical brackets. |
solv-int/9910012 | Form factors of the SU(2) invariant massive Thirring model with boundary reflection | H.Furutsu, T.Kojima and Y.-H.Quano | solv-int hep-th nlin.SI | https://arxiv.org/abs/solv-int/9910012 | 2016-12-28 | The SU(2) invariant massive Thirring model with a boundary is considered on the basis of the vertex operator approach. The bosonic formulae are presented for the vacuum vector and its dual in the presence of the boundary. The integral representations are also given for form factors of the present model. |
solv-int/9911001 | Canonical transformations of the time for the Toda lattice and the Holt system | Andrey Tsiganov | solv-int nlin.SI | https://arxiv.org/abs/solv-int/9911001 | 2009-10-31 | For the Toda lattice and the Holt system we consider properties of canonical transformations of the extended phase space, which preserve integrability. The separated variables are invariant under change of the time. On the other hand, mapping of the time induces transformations of the action-angles variables and a shift of the generating function of the B\"{a}cklund transformation. |
solv-int/9911002 | Introduction to the functions on compact Riemann surfaces and theta-functions | D.Korotkin | solv-int nlin.SI | https://arxiv.org/abs/solv-int/9911002 | 2007-05-23 | We collect some classical results related to analysis on the Riemann surfaces. The notes may serve as an introduction to the field: we suppose that the reader is familiar only with the basic facts from topology and complex analysis. the treatment is organized to give a background for further applications to non-linear differential equations. |
solv-int/9911003 | Resonant Bifurcations | Cicogna G | solv-int nlin.SI | https://arxiv.org/abs/solv-int/9911003 | 2007-05-23 | We consider dynamical systems depending on one or more real parameters, and assuming that, for some ``critical'' value of the parameters, the eigenvalues of the linear part are resonant, we discuss the existence -- under suitable hypotheses -- of a general class of bifurcating solutions in correspondence to this resonance. These bifurcating solutions include, as particular cases, the usual stationary and Hopf bifurcations. The main idea is to transform the given dynamical system into normal form (in the sense of Poincar\'e-Dulac), and to impose that the normalizing transformation is convergent, using the convergence conditions in the form given by A. Bruno. Some specially interesting situations, including the cases of multiple-periodic solutions, and of degenerate eigenvalues in the presence of symmetry, are also discussed with some detail. |
solv-int/9911004 | Integrable deformations of oscillator chains from quantum algebras | Angel Ballesteros and Francisco J. Herranz | solv-int math.QA nlin.SI | https://arxiv.org/abs/solv-int/9911004 | 2009-10-31 | A family of completely integrable nonlinear deformations of systems of N harmonic oscillators are constructed from the non-standard quantum deformation of the sl(2,R) algebra. Explicit expressions for all the associated integrals of motion are given, and the long-range nature of the interactions introduced by the deformation is shown to be linked to the underlying coalgebra structure. Separability and superintegrability properties of such systems are analysed, and their connection with classical angular momentum chains is used to construct a non-standard integrable deformation of the XXX hyperbolic Gaudin system. |
solv-int/9911005 | A note on real forms of the complex N=4 supersymmetric Toda chain hierarchy in real N=2 and N=4 superspaces | F.Delduc, A.Sorin | solv-int hep-th math-ph math.MP nlin.SI | https://arxiv.org/abs/solv-int/9911005 | 2009-10-31 | Three inequivalent real forms of the complex N=4 supersymmetric Toda chain hierarchy (Nucl. Phys. B558 (1999) 545, solv-int/9907004) in the real N=2 superspace with one even and two odd real coordinates are presented. It is demonstrated that the first of them possesses a global N=4 supersymmetry, while the other two admit a twisted N=4 supersymmetry. A new superfield basis in which supersymmetry transformations are local is discussed and a manifest N=4 supersymmetric representation of the N=4 Toda chain in terms of a chiral and an anti-chiral N=4 superfield is constructed. Its relation to the complex N=4 supersymmetric KdV hierarchy is established. Darboux-Backlund symmetries and a new real form of this last hierarchy possessing a twisted N=4 supersymmetry are derived. |
solv-int/9911006 | Bicomplexes and finite Toda lattices | Aristophanes Dimakis and Folkert Muller-Hoissen | solv-int nlin.SI | https://arxiv.org/abs/solv-int/9911006 | 2007-05-23 | We associate bicomplexes with the finite Toda lattice and with a finite Toda field theory in such a way that conserved currents and charges are obtained by a simple iterative construction. |
solv-int/9911007 | Separation of variables for soliton equations via their binary constrained flows | Yunbo Zeng and Wen-Xiu Ma | solv-int nlin.SI | https://arxiv.org/abs/solv-int/9911007 | 2009-10-31 | Binary constrained flows of soliton equations admitting $2\times 2$ Lax matrices have 2N degrees of freedom, which is twice as many as degrees of freedom in the case of mono-constrained flows. For their separation of variables only N pairs of canonical separated variables can be introduced via their Lax matrices by using the normal method. A new method to introduce the other N pairs of canonical separated variables and additional separated equations is proposed. The Jacobi inversion problems for binary constrained flows are established. Finally, the factorization of soliton equations by two commuting binary constrained flows and the separability of binary constrained flows enable us to construct the Jacobi inversion problems for some soliton hierarchies. |
solv-int/9911008 | Multidimensional analogs of geometric s<-->t duality | I.G. Korepanov | solv-int cond-mat gr-qc hep-lat hep-th nlin.SI | https://arxiv.org/abs/solv-int/9911008 | 2009-10-31 | The usual propetry of s<-->t duality for scattering amplitudes, e.g. for Veneziano amplitude, is deeply connected with the 2-dimensional geometry. In particular, a simple geometric construction of such amplitudes was proposed in a joint work by this author and S.Saito (solv-int/9812016). Here we propose analogs of one of those amplitudes associated with multidimensional euclidean spaces, paying most attention to the 3-dimensional case. Our results can be regarded as a variant of "Regge calculus" intimately connected with ideas of the theory of integrable models. |
solv-int/9911009 | Equations and Integrals of Motion in Discrete Integrable $A_{k-1}$ Algebra Models | A. P. Protogenov and V. A. Verbus | solv-int hep-th nlin.SI | https://arxiv.org/abs/solv-int/9911009 | 2007-05-23 | We study integrals of motion for Hirota bilinear difference equation that is satisfied by the eigenvalues of the transfer-matrix. The combinations of the eigenvalues of the transfer-matrix are found, which are integrals of motion for integrable discrete models for the $A_{k-1}$ algebra with zero and quasiperiodic boundary conditions. Discrete analogues of the equations of motion for the Bullough-Dodd model and non-Abelian generalization of Liouville model are obtained. |
solv-int/9912001 | Construction of variable mass sine-Gordon and other novel inhomogeneous quantum integrable models | Anjan Kundu | solv-int nlin.SI | https://arxiv.org/abs/solv-int/9912001 | 2007-05-23 | The inhomogeneity of the media or the external forces usually destroy the integrability of a system. We propose a systematic construction of a class of quantum models, which retains their exact integrability inspite of their explicit inhomogeneity. Such models include variable mass sine-Gordon model, cylindrical NLS, spin chains with impurity, inhomogeneous Toda chain, the Ablowitz-Ladik model etc. |
solv-int/9912002 | Quantum Lax scheme for Ruijsenaars models | Branislav Jurco, Peter Schupp | solv-int nlin.SI | https://arxiv.org/abs/solv-int/9912002 | 2007-05-23 | We develop a quantum Lax scheme for IRF models and difference versions of Calogero-Moser-Sutherland models introduced by Ruijsenaars. The construction is in the spirit of the Adler-Kostant-Symes method generalized to the case of face Hopf algebras and elliptic quantum groups with dynamical R-matrices. |
solv-int/9912003 | N=4 Sugawara construction on affine sl(2|1), sl(3) and mKdV-type superhierarchies | E. Ivanov (1), S. Krivonos (1), F. Toppan (2) ((1) JINR, Dubna, Russia, (2) CBPF, Rio d.J., Brazil) | solv-int hep-th nlin.SI | https://arxiv.org/abs/solv-int/9912003 | 2009-10-31 | The local Sugawara constructions of the "small" N=4 SCA in terms of supercurrents of N=2 extensions of the affinization of the sl(2|1) and sl(3) algebras are investigated. The associated super mKdV type hierarchies induced by N=4 SKdV ones are defined. In the sl(3) case the existence of two inequivalent Sugawara constructions is found. The long one involves all the affine sl(3)-valued currents, while the "short" one deals only with those from the subalgebra sl(2)\oplus u(1). As a consequence, the sl(3)-valued affine superfields carry two inequivalent mKdV type super hierarchies induced by the correspondence between "small" N=4 SCA and N=4 SKdV hierarchy. However, only the first hierarchy posseses genuine global N=4 supersymmetry. We discuss peculiarities of the realization of this N=4 supersymmetry on the affine supercurrents. |
solv-int/9912004 | Integrable Couplings of Soliton Equations by Perturbations I. A General Theory and Application to the KdV Hierarchy | Wen-Xiu Ma | solv-int nlin.SI | https://arxiv.org/abs/solv-int/9912004 | 2007-05-23 | A theory for constructing integrable couplings of soliton equations is developed by using various perturbations around solutions of perturbed soliton equations being analytic with respect to a small perturbation parameter. Multi-scale perturbations can be taken and thus higher dimensional integrable couplings can be presented. The theory is applied to the KdV soliton hierarchy. Infinitely many integrable couplings are constructed for each soliton equation in the KdV hierarchy, which contain integrable couplings possessing quadruple Hamiltonian formulations and two classes of hereditary recursion operators, and integrable couplings possessing local 2+1 dimensional bi-Hamiltonian formulations and consequent 2+1 dimensional hereditary recursion operators. |
solv-int/9912005 | Generalized KP hierarchy: M\"obius Symmetry, Symmetry Constraints and Calogero-Moser System | L.V. Bogdanov (L.D. Landau ITP, Moscow) and B.G. Konopelchenko (Universita di Lecce, Italy) | solv-int nlin.SI | https://arxiv.org/abs/solv-int/9912005 | 2007-05-23 | Analytic-bilinear approach is used to study continuous and discrete non-isospectral symmetries of the generalized KP hierarchy. It is shown that M\"obius symmetry transformation for the singular manifold equation leads to continuous or discrete non-isospectral symmetry of the basic (scalar or multicomponent KP) hierarchy connected with binary B\"acklund transformation. A more general class of multicomponent M\"obius-type symmetries is studied. It is demonstrated that symmetry constraints of KP hierarchy defined using multicomponent M\"obius-type symmetries give rise to Calogero-Moser system. |
solv-int/9912006 | Group Theoretical Properties and Band Structure of the Lame Hamiltonian | Hui Li, Dimitri Kusnezov, Francesco Iachello | solv-int nlin.SI | https://arxiv.org/abs/solv-int/9912006 | 2009-10-31 | We study the group theoretical properties of the Lame equation and its relation to su(1,1) and su(2). We compute the band structure, dispersion relation and transfer matrix and discuss the dynamical symmetry limits. |
solv-int/9912007 | Dynamical Symmetry Approach to Periodic Hamiltonians | Hui Li, Dimitri Kusnezov (Yale) | solv-int nlin.SI | https://arxiv.org/abs/solv-int/9912007 | 2009-10-31 | We show that dynamical symmetry methods can be applied to Hamiltonians with periodic potentials. We construct dynamical symmetry Hamiltonians for the Scarf potential and its extensions using representations of su(1,1) and so(2,2). Energy bands and gaps are readily understood in terms of representation theory. We compute the transfer matrices and dispersion relations for these systems, and find that the complementary series plays a central role as well as non-unitary representations. |
solv-int/9912008 | The Pfaff lattice, Matrix integrals and a map from Toda to Pfaff | M. Adler and P. van Moerbeke | solv-int nlin.SI | https://arxiv.org/abs/solv-int/9912008 | 2007-05-23 | We study the Pfaff lattice, introduced by us in the context of a Lie algebra splitting of gl(infinity) into sp(infinity) and lower-triangular matrices. We establish a set of bilinear identities, which we show to be equivalent to the Pfaff Lattice. In the semi-infinite case, the tau-functions are Pfaffians; interesting examples are the matrix integrals over symmetric matrices (symmetric matrix integrals) and matrix integrals over self-dual quaternionic Hermitean matrices (symplectic matrix integrals). There is a striking parallel of the Pfaff lattice with the Toda lattice, and more so, there is a map from one to the other. In particular, we exhibit two maps, dual to each other, (i) from the the Hermitean matrix integrals to the symmetric matrix integrals, and (ii) from the Hermitean matrix integrals to the symplectic matrix integrals. The map is given by the skew-Borel decomposition of a skew-symmetric operator. We give explicit examples for the classical weights. |
solv-int/9912009 | Quantum Lax Pair From Yang-Baxter Equations | A. Lima-Santos | solv-int hep-th nlin.SI | https://arxiv.org/abs/solv-int/9912009 | 2010-11-16 | We show explicitly how to construct the quantum Lax pair for systems with open boundary conditions. We demonstrate the method by applying it to the Heisenberg XXZ model with general integrable boundary terms. |
solv-int/9912010 | Real forms of the complex twisted N=2 supersymmetric Toda chain hierarchy in real N=1 and twisted N=2 superspaces | Olaf Lechtenfeld, Alexander Sorin | solv-int hep-th math-ph math.MP nlin.SI | https://arxiv.org/abs/solv-int/9912010 | 2017-02-08 | Three nonequivalent real forms of the complex twisted N=2 supersymmetric Toda chain hierarchy (solv-int/9907021) in real N=1 superspace are presented. It is demonstrated that they possess a global twisted N=2 supersymmetry. We discuss a new superfield basis in which the supersymmetry transformations are local. Furthermore, a representation of this hierarchy is given in terms of two twisted chiral N=2 superfields. The relations to the s-Toda hierarchy by H. Aratyn, E. Nissimov and S. Pacheva (solv-int/9801021) as well as to the modified and derivative NLS hierarchies are established. |
solv-int/9912011 | Liouville equation under perturbation | L.A.Kalyakin (Institute of Mathematics, Ufa Science Centre, Russian Acad. of Sciences) | solv-int nlin.SI | https://arxiv.org/abs/solv-int/9912011 | 2007-05-23 | Small perturbation of the Liouville equation under smooth initial data is considered. Asymptotic solution which is available for a long time interval is constructed by the two scale method. |
solv-int/9912012 | Whitham-Toda Hierarchy in the Laplacian Growth Problem | Mark Mineev-Weinstein and Anton Zabrodin | solv-int cond-mat.stat-mech hep-th nlin.PS nlin.SI | https://arxiv.org/abs/solv-int/9912012 | 2010-05-27 | The Laplacian growth problem in the limit of zero surface tension is proved to be equivalent to finding a particular solution to the dispersionless Toda lattice hierarchy. The hierarchical times are harmonic moments of the growing domain. The Laplacian growth equation itself is the quasiclassical version of the string equation that selects the solution to the hierarchy. |
solv-int/9912013 | Singular solution of the Liouville equation under perturbation | L.A.Kalyakin (Institute of Mathematics, Ufa Science Centre, Russian Acad. of Sciences) | solv-int nlin.SI | https://arxiv.org/abs/solv-int/9912013 | 2007-05-23 | Small perturbation of the Liouville equation under singular initial data is considered. An asymptotics of the singular solution is constructed by the method which is similar to Bogolubov -- Krylov one. The main object is an asymptotics of the singular lines. |
solv-int/9912014 | Vertex operator solutions to the discrete KP-hierarchy | Mark Adler and Pierre van Moerbeke | solv-int nlin.SI | https://arxiv.org/abs/solv-int/9912014 | 2009-10-31 | Vertex operators, which are disguised Darboux maps, transform solutions of the KP equation into new ones. In this paper, we show that the bi-infinite sequence obtained by Darboux transforming an arbitrary KP solution recursively forward and backwards, yields a solution to the discrete KP-hierarchy. The latter is a KP hierarchy where the continuous space x-variable gets replaced by a discrete n-variable. The fact that these sequences satisfy the discrete KP hierarchy is tantamount to certain bilinear relations connecting the consecutive KP solutions in the sequence. At the Grassmannian level, these relations are equivalent to a very simple fact, which is the nesting of the associated infinite-dimensional planes (flag). It turns out that many new and old systems lead to such discrete (semi-infinite) solutions, like sequences of soliton solutions, with more and more solitons, sequences of Calogero-Moser systems, having more and more particles, band matrices, etc... ; this will be developped in another paper. In this paper, as an other example, we show that the q-KP hierarchy maps, via a kind of Fourier transform, into the discrete KP hierarchy, enabling us to write down a very large class of solutions to the q-KP hierarchy. |
solv-int/9912015 | Vector NLS hierarchy solitons revisited: dressing transformation and tau function approach | Harold Blas | solv-int hep-th math-ph math.MP nlin.SI | https://arxiv.org/abs/solv-int/9912015 | 2007-05-23 | We discuss some algebraic aspects of the integrable vector non-linear Schr\"{o}dinger hierarchies (GNLS$_{r}$). These are hierarchies of zero-curvature equations constructed from affine Kac-Moody algebras $\hat{sl}_{r+1}$. Using the dressing transformation method and the tau-function formalism, we construct the N-soliton solutions of the GNLS$_{r}$ systems. The explicit matrix elements in the case of GNLS$_{1}$ are computed using level one vertex operator representations. |
solv-int/9912016 | On the Miura map between the dispersionless KP and dispersionless modified KP hierarchies | Jen-Hsu Chang and Ming-Hsien Tu | solv-int nlin.SI | https://arxiv.org/abs/solv-int/9912016 | 2009-10-31 | We investigate the Miura map between the dispersionless KP and dispersionless modified KP hierarchies. We show that the Miura map is canonical with respect to their bi-Hamiltonian structures. Moreover, inspired by the works of Takasaki and Takebe, the twistor construction of solution structure for the dispersionless modified KP hierarchy is given. |
supr-con/9411001 | Spin pseudo-gap and interplane coupling in Y_2Ba_4Cu_7O_{15}: a ^{63}Cu nuclear spin-spin relaxation study | R. Stern, M. Mali, J. Roos and D. Brinkmann (Physik-Institut, University Zurich, CH-8057 Zurich, Switzerland) | supr-con cond-mat.supr-con | https://arxiv.org/abs/supr-con/9411001 | 2008-02-03 | We report measurements of the Gaussian contribution, T_{2G}, to the plane ^{63}Cu nuclear spin--spin relaxation time in the YBa_2Cu_3O_7 and YBa_2Cu_4O_8 blocks of normal and superconducting Y_2Ba_4Cu_7O_{15}. The data confirm our previous results that adjacent CuO_2 planes have different doping levels and that these planes are strongly coupled. -- The static spin susceptibility at the anti-ferromagnetic wave vector exhibits a Curie--Weiss like temperature dependence in the normal state. -- The Y_2Ba_4Cu_7O_{15} data are incompatible with a phase diagram based on a single CuO_2 plane theory and suggest that the appearance of a spin gap implies interplane coupling. Additional data for YBa_2Cu_4O_8 and YBa_2Cu_3O_{6.982} are in accord with the single plane theory. -- The temperature dependence of T_{2G,ind} below T_c excludes isotropic s-wave superconductivity in all three compounds. |
supr-con/9411002 | Spin Dynamics of La_2CuO_4 and the Two-Dimensional Heisenberg Model | A.W. Sandvik and D.J. Scalapino, UC Santa Barbara | supr-con cond-mat.supr-con | https://arxiv.org/abs/supr-con/9411002 | 2009-10-28 | The spin-lattice relaxation rate $1/T_1$ and the spin echo decay rate $1/T_{2G}$ for the 2D Heisenberg model are calculated using quantum Monte Carlo and maximum entropy analytic continuation. The results are compared to recent experiments on La$_2$CuO$_4$, as well as predictions based on the non-linear $\sigma$-model. |
supr-con/9411003 | Density of states of a layered S/N d-wave superconductor | W. A. Atkinson and J. P. Carbotte (McMaster University) | supr-con cond-mat.supr-con | https://arxiv.org/abs/supr-con/9411003 | 2009-10-28 | We calculate the density of states of a layered superconductor in which there are two layers per unit cell. One of the layers contains a d-wave pairing interaction while the other is a normal metal. The goal of this article is to understand how the d-wave behaviour of the system is modified by the coupling between the layer-types. This coupling takes the form of coherent, single particle tunneling along the c-axis. We find that there are two physically different limits of behaviour, which depend on the relative locations of the Fermi surfaces of the two layer-types. We also discuss the interference between the interlayer coupling and pairing interaction and we find that this interference leads to features in the density of states. |
supr-con/9412001 | Onset of Vortices in Thin Superconducting Strips and Wires | I. Aranson, M. Gitterman and B. Ya. Shapiro, (Dept. of Physics and Jack and Pearl Resnick Inst. of Advanced Technology, Bar Ilan University) | supr-con cond-mat.supr-con | https://arxiv.org/abs/supr-con/9412001 | 2009-10-28 | Spontaneous nucleation and the consequent penetration of vortices into thin superconducting films and wires, subjected to a magnetic field, can be considered as a nonlinear stage of primary instability of the current-carrying superconducting state. The development of the instability leads to the formation of a chain of vortices in strips and helicoidal vortex lines in wires. The boundary of instability was obtained analytically. The nonlinear stage was investigated by simulations of the time-dependent generalized Ginzburg-Landau equation. |
supr-con/9412002 | Multiple Scattering Analysis of Cu-K EXAFS in Bi_2Sr_1.5Ca_1.5Cu_2O_8+d | J. R"ohler (U K"oln) and R. Cr"usemann (U Stuttgart) | supr-con cond-mat.supr-con | https://arxiv.org/abs/supr-con/9412002 | 2008-02-03 | We have analyzed the Cu K-EXAFS of Bi_2Sr_1.5Ca_1.5Cu_2O_8+d using a full multiple scattering analysis in a cluster with diameter d = 7.6 AA. The numerous quasi one-dimensional structural elements give rise to significant multiple scattering contributions in the EXAFS. We confirm the Sr/Ca ratio of the sample is 1:1, and one Ca atom is located close to a nominal Sr-site. At 40 K the dimpling angle in the $\rm CuO_2-plane is found to be < 3.5 degrees. |
supr-con/9501001 | Phonon Assisted Multimagnon Optical Absorption and Long Lived Two-Magnon States in Undoped Lamellar Copper Oxides | J. Lorenzana and G. A. Sawatzky | supr-con cond-mat.supr-con mtrl-th | https://arxiv.org/abs/supr-con/9501001 | 2008-06-16 | We calculate the effective charge for multimagnon infrared (IR) absorption assisted by phonons in the parent insulating compounds of cuprate superconductors and the spectra for two-magnon absorption using interacting spin-wave theory. Recent measured bands in the mid IR [Perkins et al. Phys. Rev. Lett. {\bf 71} 1621 (1993)] are interpreted as involving one phonon plus a two-magnon virtual bound state, and one phonon plus higher multimagnon absorption processes. The virtual bound state consists of a narrow resonance occurring when the magnon pair has total momentum close to $(\pi,0)$. |
supr-con/9502001 | Anomalous Normal-State Properties of High-T$_c$ Superconductors -- Intrinsic Properties of Strongly Correlated Electron Systems? | Th. Pruschke, M. Jarrell, J.K. Freericks | supr-con cond-mat.supr-con | https://arxiv.org/abs/supr-con/9502001 | 2016-09-08 | A systematic study of optical and transport properties of the Hubbard model, based on Metzner and Vollhardt's dynamical mean-field approximation, is reviewed. This model shows interesting anomalous properties that are, in our opinion, ubiquitous to single-band strongly correlated systems (for all spatial dimensions greater than one), and also compare qualitatively with many anomalous transport features of the high-T$_c$ cuprates. This anomalous behavior of the normal-state properties is traced to a ``collective single-band Kondo effect,'' in which a quasiparticle resonance forms at the Fermi level as the temperature is lowered, ultimately yielding a strongly renormalized Fermi liquid at zero temperature. |
supr-con/9502002 | Verification of a New Non-Linear IV-exponent: Simulation of the 2D Coulomb Gas with Langevin Dynamics. | Kenneth Holmlund, Petter Minnhagen (Dept. Theoretical Physics, Ume University, Sweden) | supr-con cond-mat.supr-con | https://arxiv.org/abs/supr-con/9502002 | 2016-09-08 | It has recently been suggested from scaling arguments that the non-linear IV-exponent a, for a two-dimensional superconductor is different from the exponent originally suggested by Ambegaokar et al. The relation between the new and the old exponent is a=a_AHNS-3. The new scaling behaviour is linked to the logarithmic vortex interaction and the long range time tail which this gives rise to. Consequently one may expect that the scaling behavior is generic for models which have these basic features. The simplest model of this type is the two-dimensional Coulomb gas model with Langevin dynamics. We here explicitly verify, through computer simulations, that the IV-characteristics of this model indeed scales according to the new scaling exponent a. Keywords: vortex, Coulomb gas, IV-exponent, Simulations, Langevin, 2D superconductor, thin films. |
supr-con/9502003 | Two-hole bound states in modified t-J model | M.Yu. Kuchiev and O. P. Sushkov | supr-con cond-mat.supr-con | https://arxiv.org/abs/supr-con/9502003 | 2016-09-08 | We consider modified $t-J$ model with minimum of single-hole dispersion at the points $(0,\pm \pi)$, $(\pm \pi,0)$. It is shown that two holes on antiferromagnetic background produce a bound state which properties strongly differs from the states known in the unmodified $t-J$ model. The bound state is d-wave, it has four nodes on the face of the magnetic Brillouin zone. However, in the coordinate representation it looks like as usual s-wave. |
supr-con/9503001 | Self-Organized Criticality Effect on Stability: Magneto-Thermal Oscillations in a Granular YBCO Superconductor | L. Legrand, I. Rosenman, R.G. Mints and G. Collin | supr-con cond-mat.supr-con | https://arxiv.org/abs/supr-con/9503001 | 2009-10-28 | We show that the self-organized criticality of the Bean's state in each of the grains of a granular superconductor results in magneto-thermal oscillations preceding a series of subsequent flux jumps. We find that the frequency of these oscillations is proportional to the external magnetic field sweep rate and is inversely proportional to the square root of the heat capacity. We demonstrate experimentally and theoretically the universality of this dependence that is mainly influenced by the granularity of the superconductor. |
supr-con/9504001 | Microwave Properties of Borocarbide Superconductors LnNi2B2C (Ln = Y, Er, Tm, Ho) | T. Jacobs, Balam A. Willemsen, S. Sridhar, R. Nagarajan, L. C. Gupta, Z. Hossain, Chandan Mazumdar, P. C. Canfield, B. K. Cho | supr-con cond-mat.supr-con | https://arxiv.org/abs/supr-con/9504001 | 2016-09-08 | We report measurements of the microwave surface impedance of the borocarbide family of superconductors LnNi2B2C (Ln=Y, Er, Tm, Ho). The experiments enable direct measurements of the superfluid density, and are particularly sensitive to the influence of magnetic pairbreaking. In HoNi2B2C the antiferromagnetic transition is clearly observed at zero field, and leads to a drastic reduction of the superfluid density, which recovers at lower temperatures. In ErNi2B2C the antiferromagnetic transition is not seen in zero field data. Magnetic effects are responsible for anomalies in the low temperature surface impedance below approximately 4K in HoNi2B2C and TmNi2B2C. The temperature dependence of the microwave impedance disagrees with simple BCS calculations. |
supr-con/9504002 | Microwave Surface Impedance of YBCO:123 crystals: Experiment and comparison to a d-wave model | T. Jacobs, S. Sridhar, C. T. Rieck, K. Scharnberg, T. Wolf and J. Halbritter | supr-con cond-mat.supr-con | https://arxiv.org/abs/supr-con/9504002 | 2009-10-28 | We present measurements of the microwave surface resistance Rs and the penetration depth lambda of YBCO:123 crystals. At low T obeys lambda(T) a polynomial behavior, while Rs displays a characteristic non-monotonic T-dependence. A detailed comparison of the experimental data is made to a model of d-wave superconductivity which includes both elastic and inelastic scattering. While the model reproduces the general features of the experimental data, three aspects of the parameters needed are worth noting. The elastic scattering rate required to fit the data is much smaller than measured from the normal state, the scattering phase shifts have to be close to pi/2 and a strong coupling value of the gap parameter 2\Delta(0)/kTc = 6 is needed. On the experimental side the uncertainties regarding the material parameters lambda(0) and Rs,res(0) further complicate a quantitative comparison. For one sample does Rs,res(0) agree with the intrinsic value which results from the d-wave model. |
supr-con/9505001 | Superconductivity from correlated hopping | C.D. Batista, F. Lema and A.A. Aligia | supr-con cond-mat.supr-con | https://arxiv.org/abs/supr-con/9505001 | 2009-10-28 | We consider a chain described by a next-nearest-neighbor hopping combined with a nearest-neighbor spin flip. In two dimensions this three-body term arises from a mapping of the three-band Hubbard model for CuO$_2$ planes to a generalized $t-J$ model and for large O-O hopping favors resonance-valence-bond superconductivity of predominantly $d$-wave symmetry. Solving the ground state and low-energy excitations by analytical and numerical methods we find that the chain is a Luther-Emery liquid with correlation exponent $K_{\rho} = (2-n)^2/2$, where $n$ is the particle density. |
supr-con/9505002 | Neutron Scattering Study of Crystal Field Energy Levels and Field Dependence of the Magnetic Order in Superconducting HoNi2B2C | T. E. Grigereit and J. W. Lynn (NIST, University of Maryland) R. J. Cava, J. J. Krajewski, and W. F. Peck, Jr. (Bell Labs) | supr-con cond-mat.supr-con | https://arxiv.org/abs/supr-con/9505002 | 2012-08-27 | Elastic and inelastic neutron scattering measurements have been carried out to investigate the magnetic properties of superconducting (Tc~8K) HoNi2B2C. The inelastic measurements reveal that the lowest two crystal field transitions out of the ground state occurat 11.28(3) and 16.00(2) meV, while the transition of 4.70(9) meV between these two levels is observed at elevated temperatures. The temperature dependence of the intensities of these transitions is consistent with both the ground state and these higher levels being magnetic doublets. The system becomes magnetically long range ordered below 8K, and since this ordering energy kTN ~ 0.69meV << 11.28meV the magnetic properties in the ordered phase are dominated by the ground-state spin dynamics only. The low temperature structure, which coexists with superconductivity, consists of ferromagnetic sheets of Ho{3+ moments in the a-b plane, with the sheets coupled antiferromagnetically along the c-axis. The magnetic state that initially forms on cooling, however, is dominated by an incommensurate spiral antiferromagnetic state along the c-axis, with wave vector qc ~0.054 A-1, in which these ferromagnetic sheets are canted from their low temperature antiparallel configuration by ~17 deg. The intensity for this spiral state reaches a maximum near the reentrant superconducting transition at ~5K; the spiral state then collapses at lower temperature in favor of the commensurate antiferromagnetic state. We have investigated the field dependence of the magnetic order at and above this reentrant superconducting transition. Initially the field rotates the powder particles to align the a-b plane along the field direction, demonstrating that the moments strongly prefer to lie within this plane due to the crystal field anisotropy. Upon subsequently increasing the field at |
supr-con/9506001 | Quantum Resistive Transition in Type II Superconductors under Magnetic Field | Ryusuke Ikeda (Dept. of Phys., Kyoto University) | supr-con cond-mat.supr-con | https://arxiv.org/abs/supr-con/9506001 | 2009-10-28 | It is shown that, within a Ginzburg-Landau (GL) formalism, the superconducting fluctuation is insulating at zero temperature even if the fluctuation dynamics is metallic (dissipative). Based on this fact, the low temperature behavior of the $H_{c2}$-line and the resistivity curves near a zero temperature transition are discussed. In particular, it is pointed out that the neglect of quantum fluctuations in data analysis of the dc resistivity may lead to an under-estimation of the $H_{c2}$ values near zero temperature. |
supr-con/9506002 | First-Order Vortex Lattice Melting and Magnetization of YBa$_2$Cu$_3$O$_{7-\delta} | R. Sasik and D. Stroud (The Ohio State University) | supr-con cond-mat.supr-con | https://arxiv.org/abs/supr-con/9506002 | 2009-10-28 | We present the first non-mean-field calculation of the magnetization $M(T)$ of YBa$_2$Cu$_3$O$_{7-\delta}$ both above and below the flux-lattice melting temperature $T_m(H)$. The results are in good agreement with experiment as a function of transverse applied field $H$. The effects of fluctuations in both order parameter $\psi({\bf r})$ and magnetic induction $B$ are included in the Ginzburg-Landau free energy functional: $\psi({\bf r})$ fluctuates within the lowest Landau level in each layer, while $B$ fluctuates uniformly according to the appropriate Boltzmann factor. The second derivative $(\partial^2 M/\partial T^2)_H$ is predicted to be negative throughout the vortex liquid state and positive in the solid state. The discontinuities in entropy and magnetization at melting are calculated to be $\sim 0.034\, k_B$ per flux line per layer and $\sim 0.0014$~emu~cm$^{-3}$ at a field of 50 kOe. |
supr-con/9506003 | The Flux-Line Lattice in Superconductors | Ernst Helmut Brandt (Max-Planck-Institut f\"ur Metallforschung, Stuttgart) | supr-con cond-mat.supr-con | https://arxiv.org/abs/supr-con/9506003 | 2009-10-28 | Magnetic flux can penetrate a type-II superconductor in form of Abrikosov vortices. These tend to arrange in a triangular flux-line lattice (FLL) which is more or less perturbed by material inhomogeneities that pin the flux lines, and in high-$T_c$ supercon- ductors (HTSC's) also by thermal fluctuations. Many properties of the FLL are well described by the phenomenological Ginzburg-Landau theory or by the electromagnetic London theory, which treats the vortex core as a singularity. In Nb alloys and HTSC's the FLL is very soft mainly because of the large magnetic penetration depth: The shear modulus of the FLL is thus small and the tilt modulus is dispersive and becomes very small for short distortion wavelength. This softness of the FLL is enhanced further by the pronounced anisotropy and layered structure of HTSC's, which strongly increases the penetration depth for currents along the c-axis of these uniaxial crystals and may even cause a decoupling of two-dimensional vortex lattices in the Cu-O layers. Thermal fluctuations and softening may melt the FLL and cause thermally activated depinning of the flux lines or of the 2D pancake vortices in the layers. Various phase transitions are predicted for the FLL in layered HTSC's. The linear and nonlinear magnetic response of HTSC's gives rise to interesting effects which strongly depend on the geometry of the experiment. |
supr-con/9506004 | Flux Creep and Flux Jumping | R.G. Mints | supr-con cond-mat.supr-con | https://arxiv.org/abs/supr-con/9506004 | 2009-10-28 | We consider the flux jump instability of the Bean's critical state arising in the flux creep regime in type-II superconductors. We find the flux jump field, $B_j$, that determines the superconducting state stability criterion. We calculate the dependence of $B_j$ on the external magnetic field ramp rate, $\dot B_e$. We demonstrate that under the conditions typical for most of the magnetization experiments the slope of the current-voltage curve in the flux creep regime determines the stability of the Bean's critical state, {\it i.e.}, the value of $B_j$. We show that a flux jump can be preceded by the magneto-thermal oscillations and find the frequency of these oscillations as a function of $\dot B_e$. |
supr-con/9507001 | Percolation transition of the vortex lattice and c-axis resistivity in high-temperature superconductors | E. A. Jagla and C. A. Balseiro | supr-con cond-mat.supr-con | https://arxiv.org/abs/supr-con/9507001 | 2009-10-28 | We use the three-dimensional Josephson junction array system as a model for studying the temperature dependence of the c-axis resistivity of high temperature superconductors, in the presence of an external magnetic field H applied in the c-direction. We show that the temperature at which the dissipation becomes different from zero corresponds to a percolation transition of the vortex lattice. In addition, the qualitative features of the resistivity vs. temperature curves close to the transition are obtained starting from the geometrical configurations of the vortices. The results apply to the cases H greater than 0 and H=0. |
supr-con/9507002 | Renormalization group approach to layered superconductors | Carsten Timm (Universitaet Hamburg) | supr-con cond-mat.supr-con | https://arxiv.org/abs/supr-con/9507002 | 2009-10-28 | A renormalization group theory for a system consisting of coupled superconducting layers as a model for typical high-temperature superconducters is developed. In a first step the electromagnetic interaction over infinitely many layers is taken into account, but the Josephson coupling is neglected. In this case the corrections to two-dimensional behavior due to the presence of the other layers are very small. Next, renormalization group equations for a layered system with very strong Josephson coupling are derived, taking into account only the smallest possible Josephson vortex loops. The applicability of these two limiting cases to typical high-temperature superconductors is discussed. Finally, it is argued that the original renormalization group approach by Kosterlitz is not applicable to a layered system with intermediate Josephson coupling. |
supr-con/9507003 | Low-Field Phase Diagram of Layered Superconductors: The Role of Electromagnetic Coupling | Gianni Blatter, Vadim Geshkenbein, Anatoli Larkin, and Henrik Nordborg | supr-con cond-mat.supr-con | https://arxiv.org/abs/supr-con/9507003 | 2009-10-28 | We determine the position and shape of the melting line in a layered superconductor taking the electromagnetic coupling between layers into account. In the limit of vanishing Josephson coupling we obtain a new generic reentrant low-field melting line. Finite Josephson coupling pushes the melting line to higher temperatures and fields and a new line shape $B_{{\rm m}} \propto (1-T/T_c)^{3/2}$ is found. We construct the low-field phase diagram including melting and decoupling lines and discuss various experiments in the light of our new results. |
supr-con/9507004 | Vortex Dynamics and the Hall-Anomaly: a Microscopic Analysis | Anne van Otterlo, Mikhail Feigel'man, Vadim Geshkenbein, and Gianni Blatter | supr-con cond-mat.supr-con | https://arxiv.org/abs/supr-con/9507004 | 2009-10-28 | We present a microscopic derivation of the equation of motion for a vortex in a superconductor. A coherent view on vortex dynamics is obtained, in which {\it both} hydrodynamics {\it and} the vortex core contribute to the forces acting on a vortex. The competition between these two provides an interpretation of the observed sign change in the Hall angle in superconductors with mean free path $l$ of the order of the coherence length $\xi$ in terms of broken particle-hole symmetry, which is related to details of the microscopic mechanism of superconductivity. |
supr-con/9507005 | Constants of motion in the dynamics of a 2N-junction SQUID | C. Nappi (CNR Napoli, Italy), G.Filatrella (Dept. of Physics, Salerno), and S. Pagano(CNR Napoli, Italy) | supr-con chao-dyn cond-mat.supr-con nlin.CD | https://arxiv.org/abs/supr-con/9507005 | 2009-10-28 | We show that a 2N junction SQUID (Superconducting QUantum Interference Device) made of 2N overdamped, shunted, identical junctions may be described as a system having only 6 degrees of freedom for any N > 2. This is achieved by means of the reduction introduced by Watanabe and Strogatz (Physica D, Vol. 74, (1994) p. 197) for series biased arrays. In our case 6 rather than 3 degrees of freedom are necessary to describe the system, due to the requirement of phase quantization along the superconducting loop constituting the device. Generalization to multijunction parallel arrays is straightforward. |
supr-con/9507006 | Screening current effects in Josephson junction arrays | A. Petraglia (Dept. of Physics, Lyngby) G.Filatrella (Dept. of Physics, Salerno), and G. Rotoli (Dept. of Energetics, L'Aquila) | supr-con chao-dyn cond-mat.supr-con nlin.CD | https://arxiv.org/abs/supr-con/9507006 | 2009-10-28 | The purpose of this work is to compare the dynamics of arrays of Josephson junctions in presence of magnetic field in two different frameworks: the so called XY frustrated model with no self inductance and an approach that takes into account the screening currents (considering self inductances only). We show that while for a range of parameters the simpler model is sufficiently accurate, in a region of the parameter space solutions arise that are not contained in the XY model equations. |
supr-con/9507007 | Nonlinear optical response in doped conjugated polymers | Kikuo Harigaya | supr-con chem-ph cond-mat.supr-con mtrl-th | https://arxiv.org/abs/supr-con/9507007 | 2008-02-03 | Exciton effects on conjugated polymers are investigated in soliton lattice states. We use the Su-Schrieffer-Heeger model with long-range Coulomb interactions. The Hartree-Fock (HF) approximation and the single-excitation configuration- interaction (single-CI) method are used to obtain optical absorption spectra. The third-harmonic generation (THG) at off-resonant frequencies is calculated as functions of the soliton concentration and the chain length of the polymer. The magnitude of the THG at the 10 percent doping increases by the factor about 10^2 from that of the neutral system. This is owing to the accumulation of the oscillator strengths at the lowest exciton with increasing the soliton concentration. The increase by the order two is common for several choices of Coulomb interaction strengths. |
supr-con/9508001 | Nucleation and Growth of Normal Phase in Thin Superconducting Strips | I. Aranson, B.Ya. Shapiro and V. Vinokur (ANL) | supr-con cond-mat.supr-con | https://arxiv.org/abs/supr-con/9508001 | 2009-10-28 | We investigate the kinetics of normal phase nucleation and flux line condensation in the type-II superconductors by numerical study of the time-dependent Ginzburg-Landau equation. We have shown that under the sufficient transport current the normal phase nucleates in the superconducting strips in a form of the macroscopic droplets having the multiple topological charge. We discuss the stability and the dynamics of the droplets. We found that pinning suppresses the droplet formation. |
supr-con/9508002 | $s$- and $d_{xy}$-wave components induced around a vortex in $d_{x^2-y^2}$-wave superconductors | M. Ichioka(Kyoto Univ.), N. Enomoto, N. Hayashi, and K. Machida(Okayama Univ.) | supr-con cond-mat.supr-con | https://arxiv.org/abs/supr-con/9508002 | 2009-10-28 | Vortex structure of $d_{x^2-y^2}$-wave superconductors is microscopically analyzed in the framework of the quasi-classical Eilenberger equations. If the pairing interaction contains an $s$-wave ($d_{xy}$-wave) component in addition to a $d_{x^2-y^2}$-wave component, the $s$-wave ($d_{xy}$-wave) component of the order parameter is necessarily induced around a vortex in $d_{x^2-y^2}$-wave superconductors. The spatial distribution of the induced $s$-wave and $d_{xy}$-wave components is calculated. The $s$-wave component has opposite winding number around vortex near the $d_{x^2-y^2}$-vortex core and its amplitude has the shape of a four-lobe clover. The amplitude of $d_{xy}$-component has the shape of an octofoil. These are consistent with results based on the GL theory. |
supr-con/9508003 | Superconducting, magnetic, and charge correlations in the doped two-chain Hubbard model | Yoshihiro Asai (ETL, Tsukuba, Japan) | supr-con cond-mat.supr-con | https://arxiv.org/abs/supr-con/9508003 | 2009-10-28 | Superconducting, magnetic, and charge correlation functions and dynamic spin correlation functions of the doped two-chain Hubbard model is studied with the projector Quantum Monte carlo method and Lanczos recursion method. Of the three correlation functions, the interchain singlet superconducting correlation function is the most long range. Our data is not consistent with the Luther-Emery picture. |
supr-con/9508004 | The Bean Critical State: Infinitely Unstable | Steven Spencer and Henrik Jeldoft Jensen | supr-con cond-mat.supr-con | https://arxiv.org/abs/supr-con/9508004 | 2009-10-28 | The threshold for creep in the Bean critical state is investigated. We perturb the Bean state by an energy $\Delta\epsilon$. We find that no matter how small $\Delta\epsilon$ is it will always be able to induce creep somewhere on the Bean profile. This finding has important consequences for the interpretation of low temperature creep phenomena in terms of quantum creep. |
supr-con/9508005 | Nonlinear Flux Diffusion and ac Susceptibility of Superconductors - Exact Numerical Results | Z. Kozio{\l} and R.A. Dunlap | supr-con cond-mat.supr-con | https://arxiv.org/abs/supr-con/9508005 | 2022-02-02 | The ac response of a slab of material with electrodynamic characteristics $E\sim j^{\kappa+1}$, $\kappa\geq0$, is studied numerically. From the solutions of the nonlinear diffusion equation, the fundamental and higher-order components of the harmonic susceptibility are obtained. A large portion of the data for every $\kappa$ can be scaled by a single parameter, $\xi$ =$t^{1/(\kappa+2)}\cdot H_0^{\kappa/(\kappa+2)}/D$, where $t$ is the period of the ac field at the surface, $H_0$ is its amplitude and $D$ is the slab thickness. This is, however, only an approximate scaling property: The field penetration into a nonlinear medium is a more complex phenomenon than in the linear case. In particular, the susceptibility values are not uniquely defined by a set of only two parameters, such as $\kappa$ and $\xi$, while one parameter, i.e. $t^{1/2}$/D, is sufficient to describe the electrodynamic response of a linear medium. |
supr-con/9508006 | Magnetostriction of a Superconductor: -Results from the Critical-State Model | Z. Kozio{\l} and R.A. Dunlap | supr-con cond-mat.supr-con | https://arxiv.org/abs/supr-con/9508006 | 2009-10-28 | In many cases, the critical-state theory can be treated as a suffi ciently accurate approximation for the modelling of the magnetic properties of superconductors. In the present work, the magnetostrictive hysteresis is computed for a quite general case of the modified Kim-Anderson model. The results obtained reproduce many features of the giant magnetostriction (butterfly-shaped curves) reported in the literature for measurements made on single-crystal samples of the high-temperature superconductor $Bi_2Sr_2CaCu_2O_8$. It is shown that addition of a contribution to the magnetostriction in the superconducting state which is of similar origin as in the normal state, offers a broader phenomenological interpretation of the complex magnetostriction hysteresis found in such heavy-fermion compounds as $UPt_3$, $URu_2Si_2$ or $UBe_{13}$. |
supr-con/9509001 | Langevin Simulations of Two Dimensional Vortex Fluctuations: Anomalous Dynamics and a New $IV$-exponent | Kenneth Holmlund and Petter Minnhagen | supr-con cond-mat.supr-con | https://arxiv.org/abs/supr-con/9509001 | 2009-10-28 | The dynamics of two dimensional (2D) vortex fluctuations are investigated through simulations of the 2D Coulomb gas model in which vortices are represented by soft disks with logarithmic interactions. The simulations trongly support a recent suggestion that 2D vortex fluctuations obey an intrinsic anomalous dynamics manifested in a long range 1/t-tail in the vortex correlations. A new non-linear IV-exponent a, which is different from the commonly used AHNS exponent, a_AHNS and is given by a = 2a_AHNS - 3, is confirmed by the simulations. The results are discussed in the context of earlier simulations, experiments and a phenomenological description. |
supr-con/9510001 | The string model of the Cooper pair in the anisotropic superconductor | V.D.Dzhunushaliev | supr-con cond-mat.supr-con hep-th | https://arxiv.org/abs/supr-con/9510001 | 2009-10-28 | The analogy between the Cooper pair in high temperature superconductor and the quark-antiquark pair in quantum chromodynamics (QCD) is proposed. In QCD the nonlinear chromodynamical field between a quark and an antiquark is confined to a tube. So we assume that there is the strong interaction between phonons which can confine them to some tube too. This tube is described using the nonlinear Schr\"odinger equation. We show that it has an infinite spectrum of axially symmetric (string) solutions with negative finite linear energy density. The one-dimensional nonlinear Schr\"odinger equation has a finite spectrum (hence, it has a steady-state) which describes the Cooper pair squezeed between anisotropy planes in the superconductor. It is shown that in this model the transition temperature is approximately 45 K. |
supr-con/9510002 | Polaronic optical absorption in electron-doped and hole-doped cuprates | P. Calvani, M. Capizzi, S. Lupi, P. Maselli, A. Paolone, (Dipartimento di Fisica, Universita di Roma ``La Sapienza'', Roma, Italy) and P. Roy (Laboratoire pour l'Utilization de Rayonnement Electromagnetique, Universite Paris-Sud, Orsay, France) | supr-con cond-mat.supr-con | https://arxiv.org/abs/supr-con/9510002 | 2009-10-28 | Polaronic features similar to those previously observed in the photoinduced spectra of cuprates have been detected in the reflectivity spectra of chemically doped parent compounds of high-critical-temperature superconductors, both $n$-type and $p$-type. In Nd$_2$CuO$_{4-y}$ these features, whose intensities depend both on doping and temperature, include local vibrational modes in the far infrared and a broad band centered at $\sim$ 1000 cm$^{-1}$. The latter band is produced by the overtones of two (or three) local modes and is well described in terms of a small-polaron model, with a binding energy of about 500 cm$^{-1}$. Most of the above infrared features are shown to survive in the metallic phase of Nd$_{2-x}$Ce$_x$Cu0$_{4-y}$, Bi$_2$Sr$_2$CuO$_6$, and YBa$_2$Cu$_3$O$_{7-y}$, where they appear as extra-Drude peaks. The occurrence of polarons is attributed to local modes strongly coupled to carriers, as shown by a comparison with tunneling results. |
supr-con/9511001 | Synchronization in one-dimensional array of Josephson coupled thin layers | Dmitry A. Ryndyk (Institute for Physics of Microstructures of Russian Academy of Sciencies, Nizhny Novgorod, Russia) | supr-con cond-mat.supr-con | https://arxiv.org/abs/supr-con/9511001 | 2008-02-03 | We obtain self-consistent macroscopic equations describing interlayer Josephson effect and intralayer disequilibrium in one-dimensional array of Josephson coupled layers. We show that ``nonequilibrium coupling'' can lead to effective spatial and time synchronization and formation of coherent dynamic resistive state (collective Josephson effect) in Nb-AlO-Nb stacked junctions and HTSC (intrinsic Josephson effect). We propose it to be the origin of collective switching phenomena observed in PbBiSrCaCuO. |
supr-con/9511002 | S-35 Beta Irradiation of a Tin Strip in a State of Superconducting Geometrical Metastability | V.Jeudy, J.I.Collar, T.A.Girard, D.Limagne and G.Waysand (G.P.S., Univ. Paris 7) | supr-con cond-mat.supr-con hep-ex nucl-ex | https://arxiv.org/abs/supr-con/9511002 | 2009-10-28 | We report the first energy loss spectrum obtained with a geometrically metastable type I superconducting tin strip irradiated by the beta-emission of S-35. (Nucl. Instr. Meth. A, in press) |
supr-con/9512001 | Vortex structure in $d$-wave superconductors | M. Ichioka (Kyoto), N. Hayashi, N. Enomoto and K. Machida (Okayama) | supr-con cond-mat.supr-con | https://arxiv.org/abs/supr-con/9512001 | 2009-10-28 | Vortex structure of pure $d_{x^2-y^2}$-wave superconductors is microscopically analyzed in the framework of the quasi-classical Eilenberger equations. Selfconsistent solution for the $d$-wave pair potential is obtained for the first time in the case of an isolated vortex. The vortex core structure, i.e., the pair potential, the supercurrent and the magnetic field, is found to be fourfold symmetric even in the case that the mixing of $s$-wave component is absent. The detailed temperature dependences of these quantities are calculated. The fourfold symmetry becomes clear when temperature is decreased. The local density of states is calculated for the selfconsistently obtained pair potential. From the results, we discuss the flow trajectory of the quasiparticles around a vortex, which is characteristic in the $d_{x^2-y^2}$-wave superconductors. The experimental relevance of our results to high temperature superconductors is also given. |
supr-con/9512002 | Beta Irradiation of a Geometrically Metastable Superconducting Strip Detector with a Magnetic Flux Penetration Read-Out | V.Jeudy, D.Limagne, G.Waysand, J.I.Collar and T.A.Girard (G.P.S., Univ. Paris 7) | supr-con cond-mat.supr-con | https://arxiv.org/abs/supr-con/9512002 | 2009-10-28 | Geometrical metastability, observed in superconducting type I tin flat strips, has been previously proposed as a principle for particle detection. The energy deposition of an incoming beta-particle induces the rupture of the metastability and consequently the penetration of multiquantum flux tubes into a superconducting tin strip. We present here the first absorption spectra from two beta sources, which demonstrate the linearity and energy-resolution of these detectors (presented at the 6th International Workshop on Low Temperature Detectors for Dark Matter and Neutrinos (LTD-6), Interlaken, Switzerland, Sept. 1995) |
supr-con/9512003 | Vortex structure and resistive transitions in high-Tc superconductors | E.A.Jagla and C. A. Balseiro | supr-con cond-mat.supr-con | https://arxiv.org/abs/supr-con/9512003 | 2009-10-28 | The nature of the resistive transition for a current applied parallel to the magnetic field in high-Tc materials is investigated by numerical simulation on the three dimensional Josephson junction array model. It is shown by using finite size scaling that for samples with disorder the critical temperature Tp for the c axis resistivity corresponds to a percolation phase transition of vortex lines perpendicularly to the applied field. The value of Tp is higher than the critical temperature for j perpendicular to H, but decreases with the thickness of the sample and with anisotropy. We predict that critical behavior around Tp should reflect in experimentally accessible quantities, as the I-V curves. |
supr-con/9601001 | Updating the theoretical analysis of the weak gravitational shielding experiment | G. Modanese (INFN, Trento) | supr-con cond-mat.supr-con gr-qc hep-ph | https://arxiv.org/abs/supr-con/9601001 | 2008-02-03 | The most recent data about the weak gravitational shielding produced recently through a levitating and rotating HTC superconducting disk show a very weak dependence of the shielding value ($\sim 1 \%$) on the height above the disk. We show that whilst this behaviour is incompatible with an intuitive vectorial picture of the shielding, it is consistently explained by our theoretical model. The expulsive force observed at the border of the shielded zone is due to energy conservation. |
supr-con/9602001 | Vortex Plastic Flow, $B(x,y,H(t)), M(H(t)), J_c(B(t))$, Deep in the Bose Glass and Mott-Insulator Regimes | C. Reichhardt, C. J. Olson, J. Groth, Stuart Field, and Franco Nori | supr-con cond-mat.mtrl-sci cond-mat.supr-con | https://arxiv.org/abs/supr-con/9602001 | 2016-09-08 | We present simulations of flux-gradient-driven superconducting vortices interacting with strong columnar pinning defects as an external field $H(t)$ is quasi-statically swept from zero through a matching field $B_{\phi}$. We analyze several measurable quantities, including the local flux density $ B(x,y,H(t))$, magnetization $M(H(t))$, critical current $J_{c}(B(t))$, and the individual vortex flow paths. We find a significant change in the behavior of these quantities as the local flux density crosses $B_{\phi}$, and quantify it for many microscopic pinning parameters. Further, we find that for a given pin density $J_c(B)$ can be enhanced by maximizing the distance between the pins for $ B < B_{\phi} $. |
supr-con/9602002 | s and d-wave symmetries of the solutions of the Eliashberg equations | G. Santi, T. Jarlborg, M. Peter and M. Weger | supr-con cond-mat.supr-con | https://arxiv.org/abs/supr-con/9602002 | 2009-10-30 | We examine the different possible symmetries of the superconducting gap obtained by solving the Eliashberg equations. We consider an electron-phonon interaction in a strong coupling scenario. The Coulomb pseudopotential plays the crucial role of providing the repulsion needed to favour the d-wave symmetry. But the key parameter that allows very anisotropic solutions even with very strong coupling is the small angular range of the interaction due to predominantly electron-phonon forward scattering that is found in the high-Tc superconductors. We find both s and d-wave solutions whose stability depends mainly on the angular range of the interaction. |
supr-con/9602003 | Vortex Response and Critical Fields observed via rf penetration depth measurements on the superconductor YNi_2B_2C | S. Oxx, D. P. Choudhury, Balam A. Willemsen, H. Srikanth, S. Sridhar (Northeastern Univ), B. K. Cho, P. C. Canfield (Ames Lab) | supr-con cond-mat.supr-con | https://arxiv.org/abs/supr-con/9602003 | 2015-06-26 | Measurements of the rf penetration depth \lambda(T,H,\theta ) are used to study the superconducting order parameter, vortex dynamics in the mixed state and delineate critical fields in the borocarbide superconductor YNi_2B_2C. The lower critical field has an anomalous T dependence, H_{c1}(T)=1.12[1-(T/T_c)] kOe, which is however consistent with independent superfluid density measurements at microwave frequencies. The vortex response is dominated by viscous flux flow, indicative of extremely weak pinning, and is parametrized by a field scale H_{c2,eff}. The angular dependence of the vortex contribution \lambda(\theta) is in good agreement with the Coffey-Clem model. Structure is seen in the depairing transition in the vicinity of the upper critical field, with the existence of well-defined critical fields H_{c2a}, H_{c2b} and H_{c2c}, with the vortex field scale H_{c2,eff} closest to H_{c2b}. Overall the measurements indicate that YNi_2B_2C has a rich and unusual field dependence of its transport parameters. |
supr-con/9604001 | Vortex loops entry into type--II superconductors | Alexey V. Samokhvalov (Institute for physics of microstructures, Nizhny Novgorod, Russia) | supr-con cond-mat.supr-con | https://arxiv.org/abs/supr-con/9604001 | 2009-10-30 | The magnetic field distribution, the magnetic flux, and the free energy of an Abrikosov vortex loop near a flat surface of type--II superconductors are calculated in the London approximation. The shape of such a vortex line is a semicircle of arbitrary radius. The interaction of the vortex half--ring and an external homogeneous magnetic field applied along the surface is studied. The magnitude of the energy barrier against the vortex expansion into superconductor is found. The possibilities of formation of an equilibrium vortex line determined by the structure of the applied magnetic field by creating the expanding vortex loops near the surface of type--II superconductor are discussed. |
supr-con/9604002 | Low temperature thermal conductivity of Zn-doped YBCO: evidence for impurity-induced electronic bound states | K. Behnia(1), H. Aubin(1), L. Taillefer(2), R. Gagnon(2) ((1) Universit\'e Paris-Sud (2) McGill University) | supr-con cond-mat.supr-con | https://arxiv.org/abs/supr-con/9604002 | 2008-02-03 | The thermal conductivity of Zn-doped YBCO crystals was studied at low temperature (0.15 < T < 0.8 K) for different concentrations of Zn impurities. A small amount of Zn induces a dramatic decrease in the non-linear component of the low-temperature thermal conductivity. Moreover, the magnitude of the linear component (obtained by extrapolating the data to T=0) is found to depend on Zn concentration. After an initial decrease, this linear term, associated with the electronic contribution to the conductivity, increases with increasing Zn dopage. Such an increase is consistent with the introduction of low-energy excitations by Zn impurities as expected for a $d_{x^2-y^2}$ superconducting state in contrast to an anisotropic s-wave gap. The results are compared to quantitative predictions of available theoretical models. |
supr-con/9605001 | Irreversible magnetization in thin YBCO films rotated in external magnetic field | R. Prozorov, A. Poddar, E. Sheriff, A. Shaulov, Y. Yeshurun (Institute for Superconductivity, Physics Department, Bar-Ilan University, Ramat-Gan, Israel) | supr-con cond-mat.supr-con | https://arxiv.org/abs/supr-con/9605001 | 2009-10-30 | The magnetization M of a thin YBaCuO film is measured as a function of the angle $\theta $ between the applied field H and the c-axis. For fields above the first critical field, but below the Bean's field for first penetration H*, M is symmetric with respect to $\theta =\pi $ and the magnetization curves for forward and backward rotation coincide. For H>H* the curves are asymmetric and they do not coincide. These phenomena have a simple explanation in the framework of the Bean critical state model. |
supr-con/9605002 | Coupling of Josephson flux-flow oscillators to an external RC load | C. Soriano, G. Costabile, R. D. Parmentier (INFM & Dept. Physics, Univ. Salerno) | supr-con cond-mat.supr-con | https://arxiv.org/abs/supr-con/9605002 | 2009-10-30 | We investigate by numerical simulations the behavior of the power dissipated in a resistive load capacitively coupled to a Josephson flux flow oscillator and compare the results to those obtained for a d.c. coupled purely resistive load. Assuming realistic values for the parameters R and C, both in the high- and in the low-Tc case the power is large enough to allow the operation of such a device in applications. |
supr-con/9606001 | New Universality Class in the Superconductive Phase Transition | Hagen Kleinert and Adriaan Schakel | supr-con cond-mat.supr-con | https://arxiv.org/abs/supr-con/9606001 | 2008-02-03 | The superconductive phase transition in the Ginzburg-Landau theory (or Coulomb-Higgs phase transition of scalar QED in 3D) is discussed in a dual formulation which focuses on the magnetic rather than the electric excitations of the system. Renormalization group analysis of the dual formulation reveals the transition to be of second order and of a new universality class. Whereas coherence length and specific heat have XY-model exponents, the magnetic penetration depth shows mean-field behavior. Experimental evidence for these predictions is discussed. |
supr-con/9606002 | Star-shaped Local Density of States around Vortices in a Type II Superconductor | N. Hayashi, M. Ichioka, K. Machida (Okayama Univ.) | supr-con cond-mat.supr-con | https://arxiv.org/abs/supr-con/9606002 | 2009-10-30 | The electronic structure of vortices in a type II superconductor is analyzed within the quasi-classical Eilenberger framework. The possible origin of a sixfold ``star'' shape of the local density of states, observed by scanning tunneling microscope experiments on NbSe$_2$, is examined in the light of the three effects; the anisotropic pairing, the vortex lattice, and the anisotropic density of states at the Fermi surface. Outstanding features of split parallel rays of this star are well explained in terms of an anisotropic $s$-wave pairing. This reveals a rich internal electronic structure associated with a vortex core. |
supr-con/9606003 | Plastic vortex-creep in YBa$_2$Cu$_3$O$_{7-x}$ crystals | Y. Abulafia, A. Shaulov, Y. Wolfus, R. Prozorov, L. Burlachkov, and Y. Yeshurun, D. Majer E. Zeldov, H. W\"uhl, V.B. Geshkenbein, V.M. Vinokur | supr-con cond-mat.supr-con | https://arxiv.org/abs/supr-con/9606003 | 2009-10-30 | Local magnetic relaxation measurements in YBa$_2$Cu$_3$O$_{7-x}$ crystals show evidence for plastic vortex-creep associated with the motion of dislocations in the vortex lattice. This creep mechanism governs the vortex dynamics in a wide range of temperatures and fields below the melting line and above the field corresponding to the peak in the ''fishtail'' magnetization. In this range the activation energy $U_{pl}$, which decreases with field, drops below the elastic (collective) creep activation energy, $U_{el}$, which increases with field. A crossover in flux dynamics from elastic to plastic creep is shown to be the origin of the fishtail in YBa$_2$Cu$_3$O$_{7-x}$. |
supr-con/9607001 | On Mean-Field Theory of Quantum Phase Transition in Granular Superconductors | M.V.Simkin (Brown University) | supr-con cond-mat.supr-con | https://arxiv.org/abs/supr-con/9607001 | 2009-10-30 | In previous work on quantum phase transition in granular superconductors, where mean-field theory was used, an assumption was made that the order parameter as a function of the mean field is a convex up function. Though this is not always the case in phase transitions, this assumption must be verified, what is done in this article. |
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