Oxygen-Vacancy-Induced Orbital Reconstruction of Ti Ions at the Interface of ${\mathrm{LaAlO}}_{3}/{\mathrm{SrTiO}}_{3}$ Heterostructures: A Resonant Soft-X-Ray Scattering Study

Oxygen-Vacancy-Induced Orbital Reconstruction of Ti Ions at the Interface of ${LaAlO}_{3} / {SrTiO}_{3}$ Heterostructures: A Resonant Soft-X-Ray Scattering Study

J. Park, B.-G. Cho, K. D. Kim, J. Koo, H. Jang, K.-T. Ko, J.-H. Park, K.-B. Lee, J.-Y. Kim, D. R. Lee, C. A. Burns, S. S. A. Seo, and H. N. Lee

Phys. Rev. Lett. 110, 017401 – Published 3 January 2013

Abstract

Resonant soft-x-ray scattering measurements have been performed to investigate interface electronic structures of ( ${LaAlO}_{3} / {SrTiO}_{3}$ ) superlattices. Resonant scattering intensities at superlattice reflections show clear evidence of degeneracy lifting in $t_{2 g}$ states of interface Ti ions. Polarization dependence of intensities indicates the energy of $d_{x y}$ states is lower by $\sim 1 eV$ than two other $t_{2 g}$ states. The energy splitting is insensitive to epitaxial strain. The orbital reconstruction is induced by oxygen vacancies and confined to the interface within two unit cells, indicating charge compensation at the polar interfaces.

Received 30 July 2012

DOI:https://doi.org/10.1103/PhysRevLett.110.017401

Authors & Affiliations

J. Park¹, B.-G. Cho¹, K. D. Kim¹, J. Koo¹, H. Jang¹, K.-T. Ko¹, J.-H. Park^1,2, K.-B. Lee^1,2,*, J.-Y. Kim², D. R. Lee³, C. A. Burns^1,4, S. S. A. Seo^5,6, and H. N. Lee^5,†

¹Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea
²Pohang Accelerator Laboratory, Pohang University of Science and Technology, Pohang 790-784, Korea
³Department of Physics, Soongsil University, Seoul 156-743, Korea
⁴Department of Physics, Western Michigan University, Kalamazoo, Michigan 49008, USA
⁵Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennesse 37831, USA
⁶Department of Physics and Atronomy, University of Kentucky, Lexington, Kentucky 40506 USA