High pressure study of low-Z superconductor Be$_{22}$Re

TL;DR

This study investigates how high pressure affects the superconducting transition temperature of Be22Re, revealing a gradual suppression of Tc up to 30 GPa and structural stability up to 154 GPa, supported by experimental and theoretical analyses.

Contribution

It provides the first high-pressure electrical resistivity and structural data on Be22Re, combining experimental measurements with DFT calculations to understand pressure effects on its superconductivity.

Findings

Tc decreases at -0.05 K/GPa with pressure

Crystal structure remains stable up to 154 GPa

Lattice stiffening dominates over electron-ion interaction changes

Abstract

With $T_c \sim 9.6~\mathrm{K}$, Be$_{22}$Re exhibits one of the highest critical temperatures among Be-rich compounds. We have carried out a series of high-pressure electrical resistivity measurements on this compound to 30 GPa. The data show that the critical temperature $T_c$ is suppressed gradually at a rate of $dT_c/dP = -0.05~\mathrm{K/GPa}$. Using density functional theory (DFT) calculations of the electronic and phonon density of states (DOS) and the measured critical temperature, we estimate that the rapid increase in lattice stiffening in Be$_{22}$Re overwhelms a moderate increase in the electron-ion interaction with pressure, resulting in the decrease in $T_c$. High pressure x-ray diffraction measurements show that the ambient pressure crystal structure of Be$_{22}$Re persists to at least 154 GPa. We discuss the relationship between low-Z Be-rich superconductors and the high-$T_c$ superhydrides.