Pressure-induced Superconductivity in Elemental Materials

Abstract

Both experimental and theoretical approaches in our search for superconductivity under pressure are reviewed. We have developed a double extreme condition of very low-temperature down to 50 mK using a ³He/⁴He dilution refrigerator and ultrahigh pressure up to 200 GPa using a diamond-anvil cell (DAC). Experimental techniques producing ultrahigh pressure as well as measuring electrical resistance, magnetization and optical response are developed especially for studying the pressure-induced superconductivity of simple systems such as elemental materials. The details of these techniques are described in §1. In §2, we review several examples of pressure-induced superconductivity observed for the first time by our group. Comparisons between experimental results and theories based on the first principles band calculations are given in §3. Finally, we point out remaining problems to be solved in further studies in the search for pressure-induced superconductivity.