Impurity effects in a vortex core in a chiral p-wave superconductor within the t-matrix approximation

TL;DR

This study investigates how non-magnetic impurities influence Andreev bound states in vortices of a two-dimensional chiral p-wave superconductor using a self-consistent t-matrix approach, revealing impurity-induced suppression of vortex core states.

Contribution

It introduces a numerical analysis of impurity effects on vortex bound states in chiral p-wave superconductors using the t-matrix approximation, highlighting impurity phase-shift dependence.

Findings

Impurities affect low energy quasiparticle spectra differently depending on scattering phase-shift.

Strong impurity scattering suppresses Andreev bound states in vortex cores.

Correlation exists between vortex core state suppression and impurity bands in the bulk.

Abstract

We study the effects of non-magnetic impurity scattering on the Andreev bound states (ABS) in an isolated vortex in a two-dimensional chiral p-wave superconductor numerically. We incorporate the impurity scattering effects into the quasiclassical Eilenberger formulation through the self-consistent $t$-matrix approximation. Within this scheme, we calculate the local density of states (LDOS) around two types of vortices: "parallel" ("anti-parallel") vortex where the phase winding of the pair-potential coming from vorticity and that coming from chirality have the same (opposite) sign. When the scattering phase-shift $\delta_0$ of each impurity is small, we find that impurities affect differently low energy quasiparticle spectrum around the two types of vortex in a way similar to that in the Born limit ($\delta_0\rightarrow 0$). For a larger $\delta_0(\leq \pi/2)$ however we find that ABS in the vortex is strongly suppressed by impurities for both types of vortex. We found that there are some correlations between the suppression of ABS near vortex cores and the low energy density of states due to impurity bands in the bulk.