• Open Access

Strong Orbital Polarization in a Cobaltate-Titanate Oxide Heterostructure

Sangjae Lee, Alex Taekyung Lee, Alexandru B. Georgescu, Gilberto Fabbris, Myung-Geun Han, Yimei Zhu, John W. Freeland, Ankit S. Disa, Yichen Jia, Mark P. M. Dean, Frederick J. Walker, Sohrab Ismail-Beigi, and Charles H. Ahn
Phys. Rev. Lett. 123, 117201 – Published 10 September 2019
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Abstract

Through a combination of experimental measurements and theoretical modeling, we describe a strongly orbital-polarized insulating ground state in an (LaTiO3)2/(LaCoO3)2 oxide heterostructure. X-ray absorption spectra and ab initio calculations show that an electron is transferred from the titanate to the cobaltate layers. The charge transfer, accompanied by a large octahedral distortion, induces a substantial orbital polarization in the cobaltate layer of a size unattainable via epitaxial strain alone. The asymmetry between in-plane and out-of-plane orbital occupancies in the high-spin cobaltate layer is predicted by theory and observed through x-ray linear dichroism experiments. Manipulating orbital configurations using interfacial coupling within heterostructures promises exciting ground-state engineering for realizing new emergent electronic phases in metal oxide superlattices.

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  • Received 11 February 2019
  • Revised 21 June 2019

DOI:https://doi.org/10.1103/PhysRevLett.123.117201

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

Published by the American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Sangjae Lee1,*, Alex Taekyung Lee2, Alexandru B. Georgescu1,3, Gilberto Fabbris4,5, Myung-Geun Han4, Yimei Zhu4, John W. Freeland5, Ankit S. Disa2, Yichen Jia1, Mark P. M. Dean4, Frederick J. Walker2, Sohrab Ismail-Beigi1,2,6, and Charles H. Ahn1,2,6

  • 1Department of Physics, Yale University, New Haven, Connecticut 06520, USA
  • 2Department of Applied Physics, Yale University, New Haven, Connecticut 06520, USA
  • 3Center for Computational Quantum Physics, Flatiron Institute, New York, New York 10010, USA
  • 4Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
  • 5Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
  • 6Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06520, USA

  • *Corresponding author. sangjae.lee@yale.edu

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Issue

Vol. 123, Iss. 11 — 13 September 2019

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