Superconductivity at 161 K in Thorium Hydride $ThH_{10}$: Synthesis and Properties

TL;DR

This study reports the synthesis of thorium hydrides with record high critical temperatures up to 161 K under high pressure, demonstrating their potential as high-temperature superconductors.

Contribution

The paper presents the experimental synthesis and characterization of new thorium hydrides with unprecedented critical temperatures and confirms theoretical predictions with measured equations of state.

Findings

ThH10 exhibits superconductivity at 161 K under high pressure.

The synthesized ThH10 has a stabilization pressure of 85 GPa.

Experimental results agree with theoretical calculations.

Abstract

Here we report targeted high-pressure synthesis of two novel high-$T_C$ hydride superconductors, $P6_3/mmc$-$ThH_9$ and $Fm\bar{3}m$-$ThH_{10}$, with the experimental critical temperatures ($T_C$) of 146 K and 159-161 K and upper critical magnetic fields ($\mu$$H_C$) 38 and 45 Tesla at pressures 170-175 Gigapascals, respectively. Superconductivity was evidenced by the observation of zero resistance and a decrease of $T_C$ under external magnetic field up to 16 Tesla. This is one of the highest critical temperatures that has been achieved experimentally in any compounds, along with such materials as $LaH_{10}$, $H_3S$ and $HgBa_2Ca_xCu_2O_{6+z}$. Our experiments show that $fcc$-$ThH_{10}$ has stabilization pressure of 85 GPa, making this material unique among all known high-$T_C$ metal polyhydrides. Two recently predicted Th-H compounds, $I4/mmm$-$ThH_4$ (> 86 GPa) and $Cmc2_1$-$ThH_6$ (86-104 GPa), were also synthesized. Equations of state of obtained thorium polyhydrides were measured and found to perfectly agree with the theoretical calculations. New phases were examined theoretically and their electronic, phonon, and superconducting properties were calculated.