Tc ENHANCEMENT IN La2-xSrxCuO4 BY ANISOTROPIC PRESSURE

Abstract

Pressure dependence of superconducting transition temperature Tc was investigated up to 8 GPa using high-quality single-crystals of La 2-x Sr x CuO 4. Variation of Tc was found to be very sensitive to the deviation from hydrostaticity as well as to the fine structure of the lattice including the tilting of the CuO 6 octahedra or the buckling of the CuO 2 planes. Compression along the c axis contributes most negatively to superconductivity. From the effect of nonhydrostatic pressure, we succeeded in estimating the potential value of Tc at ambient pressure in the tetragonal phase, which was found to be much higher than in the orthorhombic phase. Utilizing anisotropic strains induced by nonhydrostatic pressure, furthermore, we controlled the lattice and achieved the highest Tc of 51.6 K ever reported for La-214.