Pressure-induced superconductivity in topological parent compound Bi ₂ Te ₃

TLDR

Bi₂Te₃ is a theoretically predicted topological insulator with a single Dirac‑cone surface state confirmed by photoemission experiments. The study reports that applying pressure induces superconductivity (≈3 K) in hole‑doped Bi₂Te₃ single crystals. The authors discuss that the pressure‑induced superconducting bulk state could itself be a topological superconductor. First‑principles calculations show the electronic structure remains topologically nontrivial under pressure, the Dirac surface states remain distinct from bulk states, and the proximity between bulk superconductivity and surface states could host Majorana fermions.

Abstract

Bi2Te3 compound has been theoretically predicted (1) to be a topological insulator, and its topologically non-trivial surface state with a single Dirac cone has been observed in photoemission experiments (2). Here we report that superconductivity (Tc^~3K) can be induced in Bi2Te3 as-grown single crystal (with hole-carriers) via pressure. The first-principles calculations show that the electronic structure under pressure remains to be topologically nontrivial, and the Dirac-type surface states can be well distinguished from bulk states at corresponding Fermi level. The proximity effect between superconducting bulk states and Dirac-type surface state could generate Majorana fermions on the surface. We also discuss the possibility that the bulk state could be a topological superconductor.