Description:

Title: Quasiclassical Theory of Spin Imbalance in a Normal Metal-Supercond uctor Heterostructure with a Spin-Active Interface

Speaker: Dr. Oleksii Shevtsov, Northwestern University

Abstract: Non-equilibrium phenomena in superconductors have attracted much attention since the first experiments on charge imbalance in early 1970's. Nowadays a new promising line of research lies at an intersection between superconductivi ty and spintronics. Here we develop a quasiclassical theory of a single junction between a normal metal and a superconductor with a spin-active interface at finite bias voltages. Due to spin-mixing and spin-filtering effects of the interface a non-equilibrium magnetization (or spin imbalance) is induced at the superconducting side of the junction, which relaxes to zero in the bulk. A peculiar feature of the system is the presence of interface-induc ed Andreev bound states, which influence the magnitude and the decay length of spin imbalance [1]. Recent experiments on spin-charge density separation in supercoducting wires [2,3] required external magnetic field for observing spin signal via non-local measurements. Here we propose an alternative way to observe spin imbalance without applying magnetic field. Besides, our results for finite bias voltages allow for an indirect bound state spectroscopy.

[1] O. Shevtsov and T. Lofwander, Phys. Rev. B 90, 085432 (2014)

[2] M. J. Wolf et al., Phys. Rev. B 87, 024517 (2013)

[3] C. H. L. Quay et al., Nat. Phys. 9, 84-88 (2013)

Keywords: Physics, Astronomy, CMP