Dynamical control of orbital occupations via a ferroelectric-induced polar state in metallic manganites

TL;DR

This study demonstrates how ferroelectric polarization switching at interfaces can dynamically control orbital occupations in manganites, leading to significant orbital splitting changes verified through theory and experiments.

Contribution

It introduces a method to modulate orbital populations at ferroelectric/manganite interfaces via polarization switching, a novel approach not previously demonstrated.

Findings

Orbital occupation can change by up to 10% through ferroelectric switching.

Interfacial polar displacements induce large orbital splittings absent in bulk materials.

Experimental verification confirms the predicted interfacial polar state and orbital effects.

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 show how to dynamically modulate the orbital populations on Mn atoms at ferroelectric/manganite interfaces by switching the ferroelectric polarization. The change in orbital occupation can be as large as 10\%, greatly exceeding that of bulk manganites. This flippable 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 {\it ab initio} theory, epitaxial thin film growth, and scanning transmission electron microscopy to verify the predicted interfacial polar state and concomitant orbital splittings.