Interface effect and its doping dependence in La1-xSrxMnO3/SrTiO3 supertattices

We have investigated the interface effect on magnetic and transport properties in the superlattices composed of ferromagnetic La1-xSrMnO3 (LSMO) and non magnetic SrTiO3 (STO) (x = 0.2,03, 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.