Majorana bands, Berry curvature, and thermal Hall conductivity in the vortex state of a chiral p-wave superconductor

TL;DR

This paper develops a microscopic theory of Majorana quasiparticle bands in a chiral p-wave superconductor vortex lattice, revealing their topological properties and impact on thermal Hall conductivity.

Contribution

It introduces a comprehensive microscopic approach to Majorana bands, including Wannier functions and a tight-binding model, highlighting their topological nature and effects on thermal transport.

Findings

Majorana bands can be topologically trivial or nontrivial depending on intervortex hopping signs.

The topology influences the temperature dependence of the thermal Hall conductivity.

The study provides a link between microscopic quasiparticle properties and macroscopic thermal responses.

Abstract

Majorana quasiparticles localized in vortex cores of a chiral p-wave superconductor hybridize with one another to form bands in a vortex lattice. We begin by solving a fully microscopic theory describing all quasiparticle bands in a chiral p-wave superconductor in magnetic field, then use this solution to build localized Wannier wavefunctions corresponding to Majorana quasiparticles. A low-energy tight-binding theory describing the intervortex hopping of these is then derived, and its topological properties---which depend crucially on the signs of the imaginary intervortex hopping parameters---are studied. We show that the energy gap between the Majorana bands may be either topologically trivial or nontrivial, depending on whether the Chern number contributions from the Majorana bands and those from the background superconducting condensate add constructively or destructively. This topology directly affects the temperature-dependent thermal Hall conductivity, which we also calculate.