Synthesis and Superconductivity in yttrium superhydrides under high pressure

TL;DR

This study synthesizes various yttrium superhydrides under high pressure, measures their superconducting temperatures, and explores their structures, advancing the search for room-temperature superconductors.

Contribution

It provides a comprehensive high-pressure synthesis and characterization of yttrium superhydrides, revealing their superconducting properties and structural details, and rules out YH10 as a candidate within studied conditions.

Findings

YH6 exhibits superconductivity at 218 K at 165 GPa

YH9 shows superconductivity at 230 K at 300 GPa

YH4 has a superconducting transition at 82 K at 167 GPa

Abstract

The flourishing rare earth superhydrides are a class of recently discovered materials that possess near-room-temperature superconductivity at high pressures, opening a new era of superconductivity research at high pressures. Among these superhydrides, yttrium superhydrides attracted great interest owing to their abundance of stoichiometries and excellent superconductivities. Here, we carried out a comprehensive study of yttrium superhydrides in a wide pressure range of 145-300 GPa. We successfully synthesized a series of superhydrides with the compositions of YH4, YH6, YH7, and YH9, and reported their superconducting transition temperatures of 82 K at 167 GPa, 218 K at 165 GPa, 29 K at 162 GPa, and 230 K at 300 GPa, respectively, which were evidenced by a sharp drop of resistivity. The structure and superconductivity of YH4, which was taken as a representative example, were also examined by X-ray diffraction measurements and the suppression of the superconductivity under external magnetic fields, respectively. Clathrate YH10 as a candidate of room-temperature superconductor was not synthesized within the studied pressure and temperature ranges of up to 300 GPa and 2000 K, respectively. The current work created a detailed platform for further searching room-temperature superconductors in polynary yttrium-based superhydrides.