Prediction of intrinsic topological superconductivity in Mn-doped GeTe monolayer from first-principles

Jiahao Mao,Kyung-Hwan Jin,Xiaoming Zhang,Mingwen Zhao,Zheng Liu,Feng Liu

doi:10.1038/s41524-021-00511-x

Abstract

The recent discovery of topological superconductors (TSCs) has sparked enormous interest. The realization of TSC requires a delicate tuning of multiple microscopic parameters, which remains a great challenge. Here, we develop a first-principles approach to quantify realistic conditions of TSC by solving self-consistently Bogoliubov-de Gennes equation based on a Wannier function construction of band structure, in presence of Rashba spin-orbit coupling, Zeeman splitting and electron-phonon coupling. We further demonstrate the power of this method by predicting the Mn-doped GeTe (Ge1-xMnxTe) monolayer—a well-known dilute magnetic semiconductor showing superconductivity under hole doping—to be a Class D TSC with Chern number of −1 and chiral Majorana edge modes. By constructing a first-principles phase diagram in the parameter space of temperature and Mn concentration, we propose the TSC phase can be induced at a lower-limit transition temperature of ~40 mK and the Mn concentration of x~0.015%. Our approach can be generally applied to TSCs with a phonon-mediated pairing, providing useful guidance for future experiments.

Highlights

The topological phase of superconductors (SC) has recently received intense research interest as the superconducting quasiparticles residing in the non-trivial gapless/zero-energy boundary states are considered a form of Majorana fermions
We demonstrate the usefulness of this method by predicting the Mn-doped GeTe (Ge1-xMnxTe) monolayer to be a topological superconductors (TSCs) by constructing a firstprinciples phase diagram in the parameter space of temperature and Mn concentration
The firstprinciples Bogoliubov-de Gennes (BdG) Hamiltonian was constructed via a Wannier function (WF) scheme, through which we found that the GeTe monolayer with the hole concentration of ~7.4 × 1013 cm−2 becomes superconducting below ~120 mK and the Ge1-xMnxTe monolayer is a Class D TSC with Tc~40 mK characterized by a non-zero Chern number and chiral Majorana edge modes

Summary

INTRODUCTION

The topological phase of superconductors (SC) has recently received intense research interest as the superconducting quasiparticles residing in the non-trivial gapless/zero-energy boundary states are considered a form of Majorana fermions. Intrinsic TSCs exhibit inherently a nontrivial superconducting gap without the need of applying an external field or constructing a heterostructure They may be pwave SCs with natural spin-triplet pairing[18,19], such as Sr2RuO420, Cu/Sr/Nb-doped Bi2Se321 and non-centrosymmetric SCs22, or swave SCs with an effective spin-triplet pairing resulting from helical spin-polarized states, such as the two-dimensional (2D) topological electronic states[23,24], and 1D25,26 and 2D Rashba electronic states[27,28,29] which belong to the so-called Class D TSC without time-reversal symmetry (TRS).

Zhang et al 2

RESULTS AND DISCUSSION

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METHODS

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CODE AVAILABILITY