Magneto-transport in LSCO high-Tc superconducting thin films

We report a crossover from insulating to metallic behaviour near optimal doping in high-T-c thin films of La2-xSrxCuO4 (LSCO) using pulsed magnetic fields to suppress superconductivity and reveal the normal state magneto-transport in the zero temperature limits. The thin film data supports the same key findings reported on LSCO single crystals: (i) that the crossover from insulating to metallic behaviour occurs near optimal doping, and (ii) that the insulating behaviour is characterized by an unusual logarithmic divergence of the resistivity as the temperature approaches zero. A new finding is that the Hall density exhibits a sudden increase at the same Sr doping level at which the insulator-to-metal crossover occurs, possibly indicating a sharp change in the Fermi surface at optimum doping.