Bulk Superconductivity in the Dirac Semimetal TlSb

TL;DR

This study identifies TlSb as a bulk superconductor with Dirac surface states, suggesting it as a promising platform for topological quantum computing due to its coexistence of superconductivity and topological states.

Contribution

First demonstration that TlSb is a Dirac semimetal and a type-II superconductor, highlighting its potential for topological quantum applications.

Findings

TlSb is a Dirac semimetal with spin-orbit coupling.

TlSb is a type-II superconductor with Tc = 4.38 K.

Coexistence of superconductivity and topological surface states in TlSb.

Abstract

A feasible strategy to realize the Majorana fermions is searching for a simple compound with both bulk superconductivity and Dirac surface states. In this paper, we performed calculations of electronic band structure, the Fermi surface and surface states, as well as measured the resistivity, magnetization, specific heat for TlSb compound with a CsCl-type structure. The band structure calculations show that TlSb is a Dirac semimetal when spin-orbit coupling is taken into account. Meanwhile, we first found that TlSb is a type-II superconductor with $T_c$ = 4.38 K, $H_{c1}$(0) = 148 Oe, $H_{c2}$(0) = 1.12 T and $\kappa_{GL}$ = 10.6, and confirmed it to be a moderately coupled s-wave superconductor. Although we can not determine which bands near the Fermi level $E_F$ to be responsible for superconductivity, its coexistence with the topological surface states implies that TlSb compound may be a simple material platform to realize the fault-tolerant quantum computations.