Superconductivity of novel tin hydrides (Sn$_n$H$_m$) under pressure

TL;DR

This study uses evolutionary algorithms to discover new stable tin hydrides under high pressure, revealing compounds with higher superconducting transition temperatures and unique hydrogen configurations, advancing the search for high-temperature superconductors.

Contribution

The paper identifies new stable tin hydrides with higher T_c and unique hydrogen structures, expanding the known phase diagram of Sn-H system under pressure.

Findings

SnH8, SnH12, and SnH14 are thermodynamically stable at high pressure.

New compounds exhibit superconducting T_c up to 97 K at 200 GPa.

Unique hydrogen configurations like H3- and H4- are observed.

Abstract

With the motivation of discovering high-temperature superconductors, evolutionary algorithm is employed to search for all stable compounds in the Sn-H system. In addition to the traditional SnH$_4$, new hydrides SnH$_8$, SnH$_{12}$ and SnH$_{14}$ are found to be thermodynamically stable at high pressure. Dynamical stability and superconductivity of tin-hydrides are systematically investigated. I$\bar{4}$m2-SnH$_8$, C2/m-SnH$_{12}$ and C2/m-SnH$_{14}$ exhibit higher superconducting transition temperatures of 81, 93 and 97 K compared to the traditional compound SnH$_4$ with T$_c$ of 52 K at 200 GPa. An interesting bent H$_3^-$ in I$\bar{4}$m2-SnH$_8$ and novel liner H$_4^-$ in C2/m-SnH$_{12}$ are observed. All the new tin-hydrides remain metallic over their predicted range of stability. The intermediate-frequency wagging and bending vibrations have more contribution to electron-phonon coupling parameter than high-frequency stretching vibrations of H$_2$ and H$_3$.