Topological superconductor candidates PdBi$_2$Te$_4$ and PdBi$_2$Te$_5$ from a generic ab initio strategy

TL;DR

This paper introduces a new ab initio strategy to identify and design topological superconductors, specifically PdBi$_2$Te$_4$ and PdBi$_2$Te$_5$, which could host Majorana zero modes for quantum computing.

Contribution

The authors develop a novel approach combining intercalation and ab initio calculations to predict and design topological superconductors with potential for realizing Majorana modes.

Findings

PdBi$_2$Te$_4$ and PdBi$_2$Te$_5$ are experimentally synthesizable SCTMs

The strategy enables calculation of the superconducting BdG Chern number from first principles

Chiral topological superconductivity can be achieved with magnetic effects

Abstract

Superconducting topological metals (SCTMs) have recently emerged as a promising platform of topological superconductivity (TSC) and Majorana zero modes(MZMs) for quantum computation. Despite their importance in both fundamental research and applications, SCTMs are very rare in nature. In addition, some superconductors with topological electronic structures have been reported recently, but a feasible program to determine their TSC properties is still lacking. Here, we propose a new strategy to design SCTMs by intercalating the superconducting units into the topological insulators. A program that characterizes the superconducting BdG Chern number of 2D BdG Hamiltonian from ab initio calculations is also developed. Following this strategy, PdBi$_2$Te$_5$ and PdBi$_2$Te$_4$ are found to be experimentally synthesizable and ideal SCTMs. Chiral TSC could be realized in such SCTMs by incorporating topological surface states with Zeeman effect, which can be realized by an external magnetic field or in proximity to ferromagnetic (FM) insulator. Our strategy provides a new method for identifying the SCTMs and TSC candidates, and the program makes it possible to design and modulate the TSC candidates from ab initio calculations.