Observation of Superconductivity at Very High Pressure and Low Temperature -Pressure-Induced High Temperature Superconductivity of Calcium-

Abstract

We have developed a combined extreme condition of very low-temperature down to 50mK and ultrahigh pressure up to 200GPa ; using a ³He/⁴He dilution refrigerator and a diamond-anvil cell (DAC). Producing techniques for ultrahigh pressure and measuring techniques for electrical resistance are developed especially for studying the pressure-induced superconductivity of simple systems such as element. For example, the pressure-induced superconductivity of calcium is reviewed which is the highest superconducting temperature in the elements.