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F.S. Bergeret A.F. Volkov K.B. Efetov 《Applied Physics A: Materials Science & Processing》2007,89(3):599-601
We review the main features of odd triplet superconductivity in superconductor-ferromagnet (S/F) structures. We discuss the
different types of superconducting condensate that can be experimentally observed and pay special attention to the triplet
component induced in a ferromagnet which is in contact with a superconductor. The triplet component is an even function of
the momentum and an odd function of the frequency and leads to novel phenomena.
PACS 74.78.Fk; 73.23.-b; 74.50.+r; 75.70.-i 相似文献
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Using a supersymmetry formalism, we reduce exactly the problem of electron motion in an external potential to a new supermatrix model valid at all distances. All approximate nonlinear sigma models obtained previously for disordered systems can be derived from our exact model using a coarse-graining procedure. As an example, we consider a model for a smooth disorder and demonstrate that using our approach does not lead to a "mode-locking" problem. As a new application, we consider scattering on strong impurities for which the Born approximation cannot be used. Our method provides a new calculational scheme for disordered and chaotic systems. 相似文献
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We investigate transport in a granular metallic system at large tunneling conductance between the grains, g(T)>1. We show that at low temperatures, T=g(T)delta, where delta is the mean energy level spacing in a single grain, the coherent electron motion at large distances dominates the physics, contrary to the high-temperature (T>g(T)delta) behavior where conductivity is controlled by the scales of the order of the grain size. In three dimensions we predict the metal-insulator transition at the bare tunneling conductance g(C)(T)=(1/6pi)ln((E(C)/delta), where E(C) is the charging energy of a single grain. Corrections to the density of states of granular metals due to the electron-electron interaction are calculated. Our results compare favorably with the logarithmic dependence of resistivity in the high-T(c) cuprate superconductors indicating that these materials may have a granular structure. 相似文献
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J. E. Bunder K. B. Efetov V. E. Kravtsov O. M. Yevtushenko M. R. Zirnbauer 《Journal of statistical physics》2007,129(5-6):809-832
Starting from Gaussian random matrix models we derive a new supermatrix field theory model. In contrast to the conventional
non-linear sigma models, the new model is applicable for any range of correlations of the elements of the random matrices.
We clarify the domain of integration for the supermatrices, and give a demonstration of how the model works by calculating
the density of states for an ensemble of almost diagonal matrices. It is also shown how one can reduce the supermatrix model
to the conventional sigma model. 相似文献
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Quenched disorder in graphene is characterized by 5 constants and experiences the logarithmic renormalization even from the spatial scales smaller than the Fermi wavelength. We derive and solve renormalization group equations (RGEs) describing the system at such scales. At larger scales, we derive a nonlinear supermatrix sigma model completely describing localization and crossovers between different ensembles. The parameters of this sigma model are determined by the solutions of the RGEs. 相似文献
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Journal of Experimental and Theoretical Physics - The concept of the order parameter is extremely useful in physics. Here, I discuss extensions of this concept to cases when the order parameter is... 相似文献
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