High pressure structural and magneto-transport studies on type-II Dirac semimetal candidate Ir2In8S: Emergence of superconductivity upon decompression

TL;DR

This study investigates the high-pressure structural and electronic changes in Ir2In8S, revealing the emergence of superconductivity upon decompression due to electronic structural modifications and impurity scattering effects.

Contribution

It reports the discovery of superconductivity in Ir2In8S induced by pressure release, highlighting the role of electronic structural changes and impurity scattering in topological semimetals.

Findings

Stable tetragonal structure up to 7 GPa

Superconductivity appears below 4K after decompression

Pressure induces irreversible structural and electronic modifications

Abstract

The structural and magneto-transport properties of type-II Dirac semimetal candidate Ir2In8S have been investigated under high pressure. The ambient tetragonal structure (P4_2/mnm) is found to be stable up to 7 GPa, above which the system takes an orthorhombic Pnnm structure, possibly destroying the Dirac cones due to the loss of the four-fold screw symmetry. In the tetragonal structure, a gradual suppression of the transverse magneto-resistance and a rapid change in the magnetic field dependence above 50K suggest possible T-dependent Fermi surface modification. In the high pressure phase, the metallic character increases marginally (as evident from the increased RRR value) accompanied with suppressed magneto-resistance, without emergence of superconductivity up to 20 GPa and down to 1.4K. Most surprisingly, upon release of pressure to 0.2 GPa, a sharp resistance drop below 4K is observed, field varying measurements confirm this as the onset of superconductivity. The observed changes of the carrier density and mobility in the pressure-released tetragonal phase indicate electronic structural modification resulting from the irreversible polyhedral distortion. A simultaneous increase in the residual resistivity and carrier density upon decompression indicates that an enhanced impurity scattering play a key role in the emergence of superconductivity in the tetragonal Ir2In8S, making it an ideal platform to study topological superconductivity.