NMR Study of the Pressure-Induced Superconductivity in the Sr₂Ca₁₂Cu₂₄O₄₁

Abstract

Pressure-induced superconductivity in a spin-ladder cuprate Sr₂Ca₁₂Cu₂₄O₄₁ has not been studied on a microscopic level thus far although the superconductivity was already discovered in 1996. We have improved high-pressure technique with a large high-quality crystal, and succeeded in studying the superconductivity using ⁶³Cu nuclear magnetic resonance (NMR). We found that the superconductivity possesses an s-wave like character in the meaning that a finite gap exists in the quasi-particle excitation.