Engineering Majorana corner modes from two-dimensional hexagonal crystals

TL;DR

This paper proposes methods to engineer second order topological superconductors with Majorana corner modes in 2D hexagonal materials using tight-binding models with nonuniform Zeeman or pairing parameters.

Contribution

It introduces two tight-binding models on hexagonal lattices to realize second order topological superconductors with Majorana corner modes, highlighting the role of nonuniform parameters.

Findings

Majorana corner modes can be engineered in 2D hexagonal materials.

Nonuniform Zeeman or pairing parameters are essential for topological phase.

Finite size effects vary between the two models.

Abstract

Second order topological insulator can be engineered from two-dimensional materials with strong spin-orbit coupling and in-plane Zeeman field. In proximity to superconductor, topological superconducting phase could be induced in the two-dimensional materials, which host Majorana corner modes at the intersection between two zigzag edges. Two types of tight binding models in hexagonal lattice, which include $p_{z}$ or $p_{x,y}$ orbit(s) in each lattice site, are applied to engineer two-dimensional materials in topological superconducting phase. In both models, the condition that induces the second order topological superconductor requires nonuniform value of either in-plane Zeeman fields or superconductor pairing parameters in two sublattices. The finite size effect of the second model is weaker than that of the first model.