Density of states in SF bilayers with arbitrary strength of magnetic scattering

We developed the self-consistent method for the calculation of the density of states $N(\epsilon)$ in the SF bilayers. It based on the quasi-classical Usadel equations and takes into account the suppression of superconductivity in the S layer due to the proximity effect with the F metal, as well as existing mechanisms of the spin dependent electron scattering. We demonstrate that the increase of the spin orbit or spin flip electron scattering rates results in completely different transformations of $N(\epsilon)$ at the free F layer interface. The developed formalism has been applied for the interpretation of the available experimental data.Comment: 5 pages, 8 figure

Josephson currents through spin-active interfaces

The Josephson coupling of two isotropic s-wave superconductors through a small, magnetically active junction is studied. This is done as a function of junction transparency and of the degree of spin-mixing occurring in the barrier. In the tunneling limit, the critical current shows an anomalous 1/T temperature dependence at low temperatures and for certain magnetic realizations of the junction. The behavior of the Josephson current is governed by Andreev bound states appearing within the superconducting gap and the position of these states in energy is tunable with the magnetic properties of the barrier. This study is done using the equilibrium part of the quasiclassical Zaitsev-Millis-Rainer-Sauls boundary condition for spin-active interfaces and a general solution of the boundary condition is found. This solution is a generalization of the one recently presented by Eschrig [M. Eschrig, Phys. Rev B 61, 9061 (2000)] for spin-conserving interfaces and allows an effective treatment of the problem of a superconductor in proximity to a magnetically active material.Comment: 8 pages + 3 eps figure

Andreev Reflection In Ferromagnet-Superconductor Junctions

The transport properties of a ferromagnet-superconductor (FS) junction are studied in a scattering formulation. Andreev reflection at the FS interface is strongly affected by the exchange interaction in the ferromagnet. The conductance G_FS of a ballistic point contact between F and S can be both larger or smaller than the value G_FN with the superconductor in the normal state, depending on the ratio of the exchange and Fermi energies. If the ferromagnet contains a tunnel barrier (I), the conductance G_FIFS exhibits resonances which do not vanish in linear response -- in contrast to the Tomasch oscillations for non-ferromagnetic materials.Comment: 8 pages, RevTeX v3.0, including 3 encapsulated postscript figures; [2017: figures included in text

Inhomogeneous magnetism induced in a superconductor at superconductor-ferromagnet interface

We study a magnetic proximity effect at superconductor (S) - ferromagnet (F) interface. It is shown that due to an exchange of electrons between the F and S metals ferromagnetic correlations extend into the superconductor, being dependent on interface parameters. We show that ferromagnetic exchange field pair breaking effect leads to a formation of subgap bands in the S layer local density of states, that accommodate only one spin-polarized quasiparticles. Equilibrium magnetization leakage into the S layer as function of SF interface quality and a value of ferromagnetic interaction have also been calculated. We show that a damped-oscillatory behavior versus distance from SF interface is a distinguished feature of the exchange-induced magnetization of the S layer.Comment: 10 pages, 7 Postscript figure

Analysis of Incident-Photon-Energy and Polarization Dependent Resonant Inelastic X-Ray Scattering from La2_{2}CuO4_{4}

We present a detailed analysis of the incident-photon-energy and polarization dependences of the resonant inelastic x-ray scattering (RIXS) spectra at the Cu $K$ edge in La$_{2}$CuO$_{4}$. Our analysis is based on the formula developed by Nomura and Igarashi, which describes the spectra by a product of an incident-photon-dependent factor and a density-density correlation function for 3d states. We calculate the former factor using the $4p$ density of states from an ab initio band structure calculation and the latter using a multiorbital tight-binding model within the Hartree-Fock approximation and the random phase approximation. We obtain spectra with rich structures in the energy-loss range 2-5 eV, which vary with varying momentum and incident-photon energy, in semi-quantitative agreement with recent experiments. We clarify the origin of such changes as a combined effect of the incident-photon-dependent factor and the density-density correlation function.Comment: 18 pages, 10 figures, accepted to JPSJ; Wrong e-mail address and present address remove