A high superconducting critical temperature ($T_c$) 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 $T_c$ only under extraordinarily high pressures, where their spectroscopic characterization and application are tightly restricted. Here we show that a $T_c$ 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 $T_c$ 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, we spectroscopically characterized the superconducting energy gap in a high-pressure superconducting phase and found that superconducting Ce respects the conventional Bardeen-Cooper-Shrieffer theory.

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• Pressure effects
• Superconductivity
• Transition temperature
• Superconductors
• Resistivity measurements