Multi-Gap superconductivity in HgS under pressure

TL;DR

This paper investigates pressure-induced structural changes in HgS, revealing a two-gap superconducting phase with a high critical temperature of 11 K in the rock salt structure, emphasizing multiband effects.

Contribution

It provides the first theoretical evidence of multiband superconductivity in HgS under pressure, explaining the high critical temperature and the origin of the superconducting phase.

Findings

Discovery of two-gap superconductivity in HgS under pressure.

Identification of the rock salt phase as the superconducting structure.

High critical temperature of 11 K explained by multiband effects.

Abstract

Mercury chalcogenides is a class of materials that exhibit diverse structural phases under pressure, hosting exotic physical properties, including topological phases and chiral phonons. In particular, recent experimental results on HgS reports a new superconducting phase at 21 GPa, whose origin is unknown. In this letter we theoretically investigate the pressure-induced structural phase transition in HgS and the emergence of superconductivity in the rock salt phase. Remarkably, we discover that the rock salt phase hosts a two-gap superconducting phase originating from distinct Fermi surfaces. The unusually high critical temperature of 11 K emerges naturally within this multiband scenario, highlighting the role of interband coupling beyond isotropic approximation. These results place HgS among the few systems where multiband superconductivity is observed.