University of Minnesota
School of Physics & Astronomy

Publications

Emergence of Triplet Correlations in Superconductor/Half Metallic Nanojunctions with Spin Active Interfaces

                                                       

by K. Halterman and O.T. Valls in Phys. Rev. B 80, 104502 (2009).

We study triplet pairing correlations induced in an SFS trilayer (where F is a ferromagnet and S an ordinary s -wave superconductor) by spin flip scattering at the interfaces, via the derivation and self consistent solution of the appropriate Bogoliubov-de Gennes equations in the clean limit. We find that the spin flip scattering generates m = ±1- triplet correlations, odd in time and study the general spatial behavior of these and of m = 0 correlations as a function of position and of spin-flip strength, Hspin- , concentrating on the case where the ferromagnet is half-metallic. For certain values of Hspin- , the triplet correlations pervade the magnetic layer and can penetrate deeply into the superconductor. The behavior we find depends very strongly on whether the singlet order parameter is in the 0 or π- state, which must in turn be determined self-consistently. We also present results for the density of states (DOS) and for the local magnetization, which, due to spin-flip processes, is not in general aligned with the magnetization of the half metal, and near the interfaces, rotates as a function of position and Hspin- . The average DOS in both F and S is shown to exhibit various subgap bound states positioned at energies that depend strongly on the particular junction state and the spin flip scattering strength.

More information at http://arxiv.org/abs/0907.2688