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RESEARCH PRODUCT

Proximity Effect in Superconducting Heterostructures with Strong Spin-Orbit Coupling and Spin Splitting

Yao LuTero T. Heikkilä

subject

suprajohtavuusField (physics)FOS: Physical sciencesField strength02 engineering and technology01 natural sciencessuprajohteetSuperconductivity (cond-mat.supr-con)0103 physical sciencesMesoscale and Nanoscale Physics (cond-mat.mes-hall)magnetismi010306 general physicsSpin-½PhysicsCondensed matter physicsCondensed Matter - Mesoscale and Nanoscale PhysicsCondensed Matter - SuperconductivitySpin–orbit interactionDisordered Systems and Neural Networks (cond-mat.dis-nn)Condensed Matter - Disordered Systems and Neural Networks021001 nanoscience & nanotechnologyFerromagnetismT-symmetryCooper pair0210 nano-technologyProximity effect (atomic physics)

description

It has been shown that singlet Cooper pairs can be converted into triplet ones and diffuse into a ferromagnet over a long distance in a phenomenon known as the long-range proximity effect (LRPE). This happens in materials with inhomogeneous magnetism or spin-orbit coupling (SOC). Most of the previous studies focus on the cases with small SOC and exchange field. However, the physics was not clear when SOC and exchange field strength are both much greater than the disorder strength. In this work, we consider a two dimensional system with a large Rashba-type SOC and exchange field in the case where only one band is partially occupied. We develop a generalized quasiclassical theory by projecting the Green function onto the partially occupied band (POB). We find that when the SOC energy scale is comparable with the exchange field, there is no LRPE. The reason is that the nonmagnetic impurities together with the large SOC and exchange field can effectively generate spin-flip scattering, which suppresses the proximity effect. We also show that when increasing either SOC or exchange field, the decay length of superconducting correlations can be significantly increased due to an approximately restored time reversal symmetry or spin rotation symmetry around the $z$ (out-of-plane) axis.

10.1103/physrevb.100.104514http://arxiv.org/abs/1905.11135