Pressure-induced superconductivity in the giant Rashba system BiTeI

TL;DR

This study reveals that BiTeI, a giant Rashba system, becomes a superconductor under high pressure, with a maximum Tc of 6 K, supported by experimental and theoretical evidence of phonon-mediated pairing.

Contribution

First demonstration of pressure-induced superconductivity in BiTeI, combining experimental measurements and theoretical calculations to elucidate its properties.

Findings

BiTeI becomes superconducting above certain pressures.

Maximum Tc observed is 6 K.

Superconductivity is bulk and phonon-mediated.

Abstract

At ambient pressure, BiTeI is the first material found to exhibit a giant Rashba splitting of the bulk electronic bands. At low pressures, BiTeI undergoes a transition from trivial insulator to topological insulator. At still higher pressures, two structural transitions are known to occur. We have carried out a series of electrical resistivity and AC magnetic susceptibility measurements on BiTeI at pressure up to ~40 GPa in an effort to characterize the properties of the high-pressure phases. A previous calculation found that the high-pressure orthorhombic P4/nmm structure BiTeI is a metal. We find that this structure is superconducting with Tc values as high as 6 K. AC magnetic susceptibility measurements support the bulk nature of the superconductivity. Using electronic structure and phonon calculations, we compute Tc and find that our data is consistent with phonon-mediated superconductivity.