Non-exponential long-range interaction of magnetic impurities in spin-orbit coupled superconductors
Abstract
The Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction of magnetic impurities in a superconductor exponentially decreases when the distance between them is larger than the superconductor's coherence length, because this interaction is mediated by quasiparticles which have a gap in their energy spectrum. At the same time, the spin-singlet superconducting condensate was always assumed to stay neutral to magnetic impurities. Due to a spin-orbit coupling (SOC), however, Cooper pairs gain an admixture of spin-triplet correlated states which provide for a link between impurity spins and an s-wave condensate. It is shown that its static Goldstone mode mediates the interaction of the spins in two-dimensional (2D) systems. This effect is considered within two models: of a clean 2D s-wave superconductor with the strong Rashba SOC and of a bilayer system combining a 2D Rashba coupled electron gas and an s-wave superconducting film. The predicted long-range interaction can have a strong effect on a spin order in superconductor-magnetic impurity systems that are expected to host Majorana fermions.
Keywords
Cite
@article{arxiv.1804.10756,
title = {Non-exponential long-range interaction of magnetic impurities in spin-orbit coupled superconductors},
author = {A. G. Mal'shukov},
journal= {arXiv preprint arXiv:1804.10756},
year = {2018}
}
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