Interface Effect and Its Doping Dependence in La1-xSrxMnO3/SrTiO3Superlattices

We have investigated the interface effect on magnetic and transport properties in the superlattices composed of ferromagnetic La 1- x Sr x MnO 3 (LSMO) and non magnetic SrTiO 3 (STO) ( x = 0.2, 0.3, and 0.4). The interface of LSMO with STO was proved to show spin-canting, the degree of which critically depends on the doping level x and the layer thickness ( t LSMO ) of LSMO. Large magnetoresistance subsisting at low temperature appears in the superlattices with specific sets of ( x , t LSMO ) parameters that shows a metal-insulator crossover behavior with appreciable spin-canting. Implications of the present results in the tunneling magnetoresistance for the LSMO/STO/LSMO junction are also discussed.