Rashba spin-orbit coupling effects in quasiparticle interference of non-centrosymmetric superconductors

TL;DR

This paper develops a theoretical framework for quasiparticle interference in non-centrosymmetric superconductors with Rashba spin-orbit coupling, revealing new spin-dependent effects and patterns that can be observed experimentally.

Contribution

The paper introduces a novel T-matrix theory approach to analyze QPI in NCS superconductors with Rashba coupling, highlighting unique spin coherence effects and cross-QPI phenomena.

Findings

Rashba coupling causes distinct charge and spin QPI patterns.

Spin anisotropy appears in spin QPI even with isotropic magnetic impurities.

Cross-QPI pattern relates to the Rashba vector and spin oscillations.

Abstract

The theory of quasiparticle interference (QPI) for non-centrosymmetric (NCS) superconductors with Rashba spin-orbit coupling is developed using T-matrix theory in Born approximation. We show that qualitatively new effects in the QPI pattern originate from the Rashba spin-orbit coupling: The resulting spin coherence factors lead to a distinct difference of charge- and spin- QPI and to an induced spin anisotropy in the latter even for isotropic magnetic impurity scattering. In particular a cross - QPI appears describing the spin oscillation pattern due to nonmagnetic impurity scattering which is directly related to the Rashba vector. We apply our theory to a 2D model for the NCS heavy fermion unconventional superconductor CePt$_3$Si and discuss the new QPI features for a gap model with accidental node lines due to its composite singlet-triplet nature.