Strain induced spin vortex and Majorana Kramer's pairs in doped topological insulators with nematic superconductivity

TL;DR

This paper demonstrates how strain-induced nematic vorticity in doped topological insulators leads to the formation of spin vortices, which host Majorana Kramer's pairs or flat bands, revealing a link between strain and Majorana fermions.

Contribution

It introduces a Ginzburg-Landau model for strain-induced vorticity and analyzes electronic states, uncovering new types of Majorana states in nematic superconductors.

Findings

Type I vortices host localized Majorana Kramer's pairs.

Type II vortices form Majorana flat bands.

Strain controls the topological Majorana states.

Abstract

Using Ginzburg-Landau approach we show that the strain of the nematic superconductor can generate a specific (nematic) vorticity. In the case of doped topological insulators that vorticity forms a spin vortex. We find two types of topologically different spin vortices that either enhance (type I) or suppress (type II) superconductivity far from the vortex core. We apply Bogoliubov-de Geunnes equations to study electronic states in the nematic superconductor with spin vortices. We find that in the case of the vortex of type I, zero-energy states are localized near the vortex core. These states can be identified as Majorana Kramer's pairs. In the case of the vortex of type II, zero-energy states form Majorana flat bands. Thus, we establish a non-trivial connection between the strain and Majorana fermions in the doped topological insulators with nematic superconductivity.