Reversible modulation of orbital occupations via an interface-induced state in metallic manganites

TL;DR

This study demonstrates reversible control of orbital occupations in manganites at ferroelectric interfaces, using ab initio calculations and experimental verification, enabling significant orbital polarization modulation for potential electronic applications.

Contribution

It reveals that ferroelectric polarization can reversibly modulate orbital populations at interfaces, a phenomenon absent in bulk materials, with potential for tunable electronic properties.

Findings

Orbital occupation can be modulated by up to 10% at interfaces.

Ferroelectric polar displacements propagate into the manganite, affecting orbital splitting.

Experimental verification confirms the presence of interfacial polar distortions.

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 inmetal 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.