Structure, Resistivity, Critical Field, Specific-Heat Jump at Tc, Meissner Effect, a.c. and d.c. Susceptibility of the High-Temperature Superconductor La2-xSrxCuO4

Abstract

The temperature dependence of the resistivity, the magnetic properties and the specific heat were investigated on sintered samples of La1.85Sr0.15CuO4 having zero resistance below 35 K. The crystal structure at 300 K (tetragonal K2NiF4-type) was refined from X-ray powder diffraction data. The d.c. susceptibility shows no indication for the existence of localized Cu2+ moments. The observation of a 60% Meissner effect and a smeared jump at Tc in the specific-heat curve prove the intrinsic character of this superconducting state. The amplitude of this jump is compatible with the DOS estimated from the Pauli susceptibility. With a critical magnetic field slope dHc2/dT|Tc = -2.5 T/K, the orbital critical field is expected to be of the order of 64 T.