20 research outputs found
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 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 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 LaCuO
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
edge in LaCuO. 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 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