Superconducting Bi2Te: pressure-induced universality in the (Bi2)m(Bi2Te3)n series

TL;DR

This study reveals pressure-induced superconductivity in Bi2Te, showing universal behavior across the (Bi2)m(Bi2Te3)n series, with high-pressure phase transitions and unconventional superconducting properties linked to strong spin-orbit interactions.

Contribution

It demonstrates superconductivity in Bi2Te under high pressure and identifies universal pressure-induced phase transitions in the (Bi2)m(Bi2Te3)n series, highlighting the need for new theoretical models.

Findings

Superconductivity in Bi2Te with Tc=8.6 K at 14.5 GPa.

Multiple high-pressure phase transitions leading to a bcc structure.

Linear Hc2(T) exceeding WHH limit, indicating unconventional superconductivity.

Abstract

Using high-pressure magnetotransport techniques we have discovered superconductivity in Bi2Te, a member of the infinitely adaptive (Bi2)m(Bi2Te3)n series, whose end members, Bi and Bi2Te3, can be tuned to display topological surface states or superconductivity. Bi2Te has a maximum Tc= 8.6 K at P= 14.5 GPa and goes through multiple high pressure phase transitions, ultimately collapsing into a bcc structure that suggests a universal behavior across the series. High-pressure magnetoresistance and Hall measurements suggest a semi-metal to metal transition near 5.4 GPa, which accompanies the hexagonal to intermediate phase transition seen via x-ray diffraction measurements. In addition, the linearity of Hc2(T) exceeds the Werthamer-Helfand-Hohenberg limit, even in the extreme spin-orbit scattering limit, yet is consistent with other strong spin-orbit materials. Considering these results in combination with similar reports on strong spin-orbit scattering materials seen in the literature, we suggest the need for a new theory that can address the unconventional nature of their superconducting states.