Inhomogeneous superconductivity probed through the elastic constant of the vortex lattice in La1.93Sr0.07CuO4

Abstract Ultrasonic measurements have been carried out in order to investigate the superconducting volume fraction in La 2− x Sr x CuO 4 ( x =0.07) single crystal, with x slightly larger than the critical point of the superconducting transition x c ∼0.06. The elastic constant of the vortex lattice, which is proportional to the superconducting volume fraction, shows a gradual increase below the superconducting transition temperature T c =14 K with decreasing temperature.