Fully gapped superconductivity in In-doped topological crystalline insulator Pb${}_{0.5}$Sn${}_{0.5}$Te

Abstract

Superconductors derived from topological insulators and topological crystalline insulators by doping have long been considered to be candidates as topological superconductors. Pb${}_{0.5}$Sn${}_{0.5}$Te is a topological crystalline insulator with mirror symmetry protected surface states on (001), (011) and (111) oriented surfaces. The superconductor (Pb${}_{0.5}$Sn${}_{0.5}$)${}_{0.7}$In${}_{0.3}$Te is induced by In doping in Pb${}_{0.5}$Sn${}_{0.5}$Te, and is thought to be a topological superconductor. Here we report the first scanning tunneling spectroscopy measurement of the superconducting state as well as the superconducting energy gap in (Pb${}_{0.5}$Sn${}_{0.5}$)${}_{0.7}$In${}_{0.3}$Te on a (001)-oriented surface. The spectrum can be well fitted by an anisotropic $s$-wave gap function of $\Delta =0.72+0.18\cos 4\theta$ meV using Dynes model. The results show that the quasi-particle density of states seem to be fully gapped without any in-gap states, in contradiction with the expectation of a topological superconductor.

5 pages, 4 figures

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Cited by in corpus (13)

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• Indium substitution effect on the topological crystalline insulator family (Pb${}_{1-x}$Sn${}_x$)${}_{1-y}$In${}_y$Te: Topological and superconducting properties
• Observation of coexisting weak localization and superconducting fluctuations in strained Sn1-xInxTe thin films
• Tip-induced Superconductivity Coexisting with Preserved Topological Properties in Line-nodal Semimetal ZrSiS
• Spin-singlet superconductivity in doped topological crystalline insulator Sn_{0.96}In_{0.04}Te
• Unusual phonon density of states and response to the superconducting transition in the In-doped topological crystalline insulator Pb${}_{0.5}$Sn${}_{0.5}$Te
• Electron-phonon coupling and superconductivity in the doped topological-crystalline insulator (Pb${}_{0.5}$Sn${}_{0.5}$)${}_{1-x}$In${}_x$Te
• Full superconducting gap in the candidate topological superconductor In${}_{1-x}$Pb${}_x$Te for x = 0.2
• Possible Topological Superconductivity in a Topological Crystalline Insulator (Pb${}_{1-x}$Sn${}_x$)${}_{1-y}$In${}_y$Te
• Unconventional superconductivity from electronic dipole fluctuations