title: Reversible modulation of orbital occupations via an interface-induced polar state in metallic manganites.
abstract: The breaking of orbital degeneracy on a transition metal cation and the resulting unequal electronic occupations of these orbitals provide a powerful lever over electron density and spin ordering in metal oxides. Here, we use ab initio calculations to show that reversibly modulating the orbital populations on Mn atoms can be achieved at ferroelectric/manganite interfaces by the presence of ferroelectric polarization on the nanoscale. The change in orbital occupation can be as large as 10%, greatly exceeding that of bulk manganites. This reversible orbital splitting is in large part controlled by the propagation of ferroelectric polar displacements into the interfacial region, a structural motif absent in the bulk and unique to the interface. We use epitaxial thin film growth and scanning transmission electron microscopy to verify this key interfacial polar distortion and discuss the potential of reversible control of orbital polarization via nanoscale ferroelectrics.
authors.affiliation: Department of Physics and ‡Department of Applied Physics and Applied Mathematics, Columbia University , New York, New York 10027, United States.
authors.forename: Hanghui
authors.initials: H
authors.lastname: Chen
authors.forename: Qiao
authors.initials: Q
authors.lastname: Qiao
authors.forename: Matthew S J
authors.initials: MS
authors.lastname: Marshall
authors.forename: Alexandru B
authors.initials: AB
authors.lastname: Georgescu
authors.forename: Ahmet
authors.initials: A
authors.lastname: Gulec
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Phillips
authors.forename: Robert F
authors.initials: RF
authors.lastname: Klie
authors.forename: Frederick J
authors.initials: FJ
authors.lastname: Walker
authors.forename: Charles H
authors.initials: CH
authors.lastname: Ahn
authors.forename: Sohrab
authors.initials: S
authors.lastname: Ismail-Beigi
keywords: Ferroelectric; manganite; orbital polarization; oxide interface