Strain effects on magnetic characteristics of ultrathin La0.7Sr0.3MnO3 in epitaxial La0.7Sr0.3MnO3/BaTiO3 superlattices

A series of La0.7Sr0.3MnO3 (LSMO)/BaTiO3 (BTO) superlattices with fixed period thickness have been deposited on SrTiO3 (001) single-crystal substrates using pulsed laser deposition. X-ray diffraction and atomic force microscopy measurements reveal well-defined superstructures with smooth surface morphology. Magnetization and (magneto-) resistance of these [(LSMO)(m)/(BTO)(n)](5) superlattices are characterized as a function of the relative thickness m/n in each period. Saturated magnetization is observed to decrease as m/n decreases. The splitting in zero-field cooling/field cooling magnetization curves and the enhanced magnetoresistance imply the coexistence and the competition of ferromagnetic and antiferromagnetic interactions in the ultrathin LSMO layers due to a magnetic inhomogeneity along the direction perpendicular to the sample surface. The inhomogeneity and the ferromagnetic/antiferromagnetic competition can be tuned by residual strain in the superlattices through designing the relative thickness of LSMO and BTO. VC 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4770485]