Superconductivity to 262 kelvin via catalyzed hydrogenation of yttrium at high pressures

TL;DR

This paper reports the synthesis of yttrium superhydride exhibiting superconductivity at 262 kelvin under high pressure, advancing the pursuit of room-temperature superconductors through catalyzed hydrogenation.

Contribution

It introduces a novel yttrium superhydride with high Tc, synthesized with palladium assistance, and provides experimental evidence of phonon-mediated superconductivity at unprecedented temperatures.

Findings

Superconductivity at 262 K observed at 182 GPa

YH9 identified as the likely synthesized phase

High upper critical magnetic field of 103 T

Abstract

Room temperature superconductivity has been achieved under high pressure in an organically derived carbonaceous sulfur hydride with a critical superconducting transition temperature (Tc) of 288 kelvin. This development is part of a new class of dense, hydrogen rich materials with remarkably high critical temperatures. Metal superhydrides are a subclass of these materials that provide a different and potentially more promising route to very high Tc superconductivity. The most promising binary metal superhydrides contain alkaline or rare earth elements, and recent experimental observations of LaH10 have shown them capable of Tc s up to 250 to 260 kelvin. Predictions have shown yttrium superhydrides to be the most promising with an estimated Tc in excess of 300 kelvin for YH10. Here we report the synthesis of an yttrium superhydride that exhibits superconductivity at a critical temperature of 262 kelvin at 182 gigapascal. A palladium thin film assists the synthesis by protecting the sputtered yttrium from oxidation and promoting subsequent hydrogenation. Phonon mediated superconductivity is established by the observation of zero resistance, an isotope effect and the reduction of Tc under an external magnetic field. The upper critical magnetic field is 103 tesla at zero temperature. We suggest YH9 is the synthesized product based on comparison of the measured Raman spectra and Tc to calculated Raman results.