High Tc superconductivity in elemental cerium under mesoscopic point contacts

One of the key objectives of modern condensed matter research is the discovery of superconductors with high critical temperatures (Tc) among chemically simple and stable materials. Elemental metals such as calcium, titanium and scandium have been reported to exhibit significantly enhanced Tc under extreme hydrostatic pressures. However, the requirement for specialized high-pressure cells restricts their spectroscopic characterization and practical applications. In this work, we demonstrate a simple and cost-effective technique to induce superconductivity in elemental cerium with a critical temperature exceeding 20 K, achieved by applying high uniaxial pressure through a sharp metallic needle pressed onto the sample. This finding is novel, as pure cerium exhibits superconductivity only under high hydrostatic pressures, with a maximum Tc of about 1.8 K even at pressures up to 54 GPa. Furthermore, for the first time, we have spectroscopically characterized the superconducting energy gap in this high-pressure phase using Andreev reflection spectroscopy.