The effect of oxygen stoichiometry at the interface of epitaxial BaTiO3/La0.7Sr0.3MnO3 bilayers on its electronic and magnetic properties

Abstract

We have studied the electronic and magnetic properties of BaTiO3 (BTO)/La0.7Sr0.3MnO3(LSMO) bilayer thin films deposited by pulse laser deposition on SrTiO3 (100) substrate. X-ray diffraction and reciprocal space mappings show that the grown bilayers are single phase and epitaxial in nature. We observed by the X-ray absorption study that the relative hybridization of t2g orbitals of Ti 3d with oxygen 2p decreases with increasing Ti3+ fraction in the BTO layer. We found the anomalies in magnetization versus temperature behaviour near the structure transition of BTO, indicating coupling of the LSMO layer with the BTO structure. We also observed the pinched M-H hysteresis loop at low 5 K in this bilayer, and this pinched behaviour completely disappeared when the BTO layer is used as the bottom layer of the bilayer. It is shown that this pinched hysteresis behaviour arises because of coupling of Ti3+ which is present at the interface in the nonstoichiometric BTO top layer with the bottom LSMO layer at the interface.