Microwave study of the high-Tc superconductor La1.8Sr0.2CuO4

Abstract

High-$T_c$ superconductivity is investigated by a microwave-cavity perturbation technique in the compound ${\mathrm{La}}_{1.8}$ ${\mathrm{Sr}}_{0.2}$Cu${\mathrm{O}}_4$. Both the microwave loss and frequency shift show a rapid decrease at 39 K, the onset of the superconducting transition. A significant microwave absorption is also observed well below the transition. The data are used to determine the sample resistivity in the normal state and characterize the superconducting transition in an applied magnetic field.