Perovskite superlattices as tailored materials of correlated electrons

A systematic study is presented on the control of magnetoelectronic properties of La1-xSrxMnO3 thin films and their superlattices. First. it is demonstrated that the orbital/spin ordering of the thin films can be controlled by tuning epitaxial strain from the substrate even at a fixed doping level. Then, we show two prototypical cases of the manganite-based superlattice, which show gigantic magnetoelectronic responses due to the spin-modification at the interfaces. In the case of superlattices composed of ferromagnetic metal La1-xSrxMnO3 (x = 0.2, 0.3, and 0.4) and non-magnetic insulator SrTiO3, the remarkable variation of magnetization with doping level indicates that spin canting is caused by the charge-transfer at the interface in a doping (x)-dependent manner. In the superlattices of La1-xSrxMnO3 (x = 0.4) and antiferromagnetic La1-xSrxFeO3 (x = 0.4), antiferromagnetic spin correlation in La1-xSrxFeO3 is transmitted to the ferromagnetic spin ordering in the La1-xSrxMnO3 layer to induce the spin canting. External magnetic field restores the ferromagnetism of La1-xSrxMnO3 near the interfaces, giving rise to large magnetoresistance subsisting to the lowest temperature in these superlattice systems. (C) 2001 Elsevier Science B.V. All rights reserved.