Superconductivity in the metallic elements at high pressures

• Under the application of ultra-high pressures, several pure elemental solids exhibit superconducting critical temperatures near 20 K.
• Some elements display pressure induced superconductivity in the vicinity of magnetic, or charge–density–wave transitions.
• This review includes a survey of the occurrence and understanding of pressure induced superconductivity in the subset of elements that are metallic at ambient pressure.

Although the highest superconducting critical temperature, TcTc, found in an elemental solid at ambient pressure is 9.2 K (niobium), under the application of ultra-high pressures, several elements exhibit TcTc values near or above 20 K. This review includes a survey of the occurrence and understanding of pressure-induced superconductivity in the subset of elements that are metallic at ambient pressure. A particular focus is directed towards those elements that display the highest superconducting critical temperatures or exhibit substantial increases in TcTc with pressure. A separate article in this issue by Shimizu will cover pressure-induced superconductivity in elements that are insulating at ambient pressure.