Perovskite superlattices as tailored materials of correlated electrons

A systematic study is presented on the control of magnetoelectronic propert ies of La1-xSrxMnO3 thin films and their superlattices. First. it is demons trated that the orbital/spin ordering of the thin films can be controlled b y tuning epitaxial strain from the substrate even at a fixed doping level. Then, we show two prototypical cases of the manganite-based superlattice, w hich 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 SrTiO 3, the remarkable variation of magnetization with doping level indicates th at spin canting is caused by the charge-transfer at the interface in a dopi ng (x)-dependent manner. In the superlattices of La1-xSrxMnO3 (x = 0.4) and antiferromagnetic La1-xSrxFeO3 (x = 0.4), antiferromagnetic spin correlati on in La1-xSrxFeO3 is transmitted to the ferromagnetic spin ordering in the La1-xSrxMnO3 layer to induce the spin canting. External magnetic field res tores the ferromagnetism of La1-xSrxMnO3 near the interfaces, giving rise t o large magnetoresistance subsisting to the lowest temperature in these sup erlattice systems. (C) 2001 Elsevier Science B.V. All rights reserved.