Above 20K conventional superconductivity in Cerium

TL;DR

This paper demonstrates that pure cerium can exhibit superconductivity above 20K under simple uniaxial pressure, a significant breakthrough in elemental superconductors, with spectroscopic evidence supporting conventional BCS behavior.

Contribution

It introduces a novel method of inducing high-temperature superconductivity in elemental cerium using uniaxial pressure, contrasting with previous high-pressure techniques.

Findings

Superconductivity in Ce exceeds 20K under uniaxial pressure.

Superconducting Ce follows conventional BCS theory.

Spectroscopic characterization of the energy gap was achieved.

Abstract

A high superconducting critical temperature (Tc) under normal laboratory conditions in a material that is chemically simple and stable, like an elemental metal, is a hitherto unattained goal of modern science and technology. Certain elemental metals are known to display reasonably high Tc only under extraordinarily high pressures where their spectroscopic characterization and application are tightly restricted. Here we show that a Tc exceeding 20 K can be realized on pure elemental Ce under uniaxial pressure created simply by pressing a sharp metallic needle on the metal. This is a breakthrough because pure Ce does not superconduct under ambient conditions and the application of 54 GPa of hydrostatic pressure yields only a low Tc of 1.8 K in the metal. In addition, by driving the area under the needle in a mechanically controlled way to the ballistic transport regime, for the first time, we spectroscopically characterized the superconducting energy gap in a high-pressure superconducting phase and found that superconducting Ce respects the conventional Bardeen-Cooper-Shrieffer (BCS) theory.