Correlations Between Magnetostriction Jumps and Flux Instabilities in La1.85Sr0.15CuO4 Single Crystal

Giant magnetostriction in a large La1.85Sr0.15CuO4 single crystal has been studied by the strain gauge technique in magnetic fields up to 12 T. For magnetic field B∥c in the temperature range between 4.2 K and 8.5 K pronounced jumps of transverse magnetostriction have been observed. Different experimental techniques have been applied in order to study the correlations between the magnetostriction jumps and flux instabilities in the material under study. The observed instabilities are strongly dependent on experimental conditions. The simple adiabatic theory seems to be insufficient to describe magnetic instabilities in high temperature superconductors.