Influence of hole depletion and depolarizing field on the BaTiO3/La0.6Sr0.4MnO3 interface electronic structure revealed by photoelectron spectroscopy and first-principles calculations

• Published in: Physical review. B, Condensed matter and materials physics Condensed matter and materials physics, 2015-12, Vol.92
• Main Authors: Popescu, D.G., Barrett, Nicholas, Chirila, Christina, Pasuk, Iuliana, Husanu, M. A.
• Format: Article
• Language: English
• Subjects: Condensed Matter; Physics
• ISSN: 1098-0121; 1550-235X
• DOI: 10.1103/PhysRevB.92.235442

The effects of the bonding mechanism and band alignment in a ferroelectric (FE) BaTiO3/ferromagneticLa0.6Sr0.4MnO3 heterostructure are studied using x-ray photoelectron spectroscopy and first-principles calculations.The band lineup at the interface is determined by a combination of band bending and polarization-inducedmodification of core-hole screening. A Schottky barrier height for electrons of 1.22 ± 0.17 eV is obtained inthe case of downwards FE polarization of the top layer. The symmetry of the bonding states is emphasizedby integrating the local density of states ±0.2 eV around the Fermi level, and strong dependence on the FEpolarization is found: upwards, polarization stabilizes Ti t2g(xy) orbitals, while downwards, polarization favorsTi t2g(yz) symmetry. It is predicted that the abrupt (La,Sr)|TiO2 interface is magnetoelectrically active, leading toa A-type antiferromagnetic coupling of the first TiO2 interface layer with the underlying manganite layer througha superexchange mechanism