High temperature superconductivity in sulfur and selenium hydrides at high pressure

TL;DR

This paper investigates high-temperature superconductivity in sulfur and selenium hydrides under high pressure, predicting new phases with critical temperatures exceeding 120 K, and highlighting their unusual superconducting properties.

Contribution

It provides new predictions of high-temperature superconducting phases in Se-H and S-H systems at lower pressures using advanced computational methods.

Findings

SeH3 exceeds 120 K superconductivity at 100 GPa

Se-H has a similar phase diagram to S-H with high Tc

Both compounds exhibit unusual superconducting properties

Abstract

Due to its low atomic mass hydrogen is the most promising element to search for high-temperature phononic superconductors. However, metallic phases of hydrogen are only expected at extreme pressures (400 GPa or higher). The measurement of a record superconducting critical temperature of 190 K in a hydrogen-sulfur compound at 200 GPa of pressure[1], shows that metallization of hydrogen can be reached at significantly lower pressure by inserting it in the matrix of other elements. In this work we re-investigate the phase diagram and the superconducting properties of the H-S system by means of minima hopping method for structure prediction and Density Functional theory for superconductors. We also show that Se-H has a similar phase diagram as its sulfur counterpart as well as high superconducting critical temperature. We predict SeH3 to exceed 120 K superconductivity at 100 GPa. We show that both SeH3 and SH3, due to the critical temperature and peculiar electronic structure, present rather unusual superconducting properties.