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Phys. Rev. Lett. 104, 036401 (2010) [4 pages]

Two-Dimensional Confinement of 3d1 Electrons in LaTiO3/LaAlO3 Multilayers

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S. S. A. Seo1,2,*, M. J. Han1,†, G. W. J. Hassink3,4, W. S. Choi1, S. J. Moon1, J. S. Kim2,‡, T. Susaki3, Y. S. Lee5, J. Yu1, C. Bernhard6, H. Y. Hwang3,7, G. Rijnders4, D. H. A. Blank4, B. Keimer2, and T. W. Noh1,§
1Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Korea
2Max-Planck-Institut für Festkörperforschung, Stuttgart D-70569, Germany
3Department of Advanced Materials Science, University of Tokyo, Kashiwa, Chiba 277-8561, Japan
4MESA+ Institute for Nanotechnology, University of Twente, Enschede NL-7500 AE, The Netherlands
5Department of Physics, Soongsil University, Seoul 156-743, Korea
6Department of Physics and Fribourg Center for Nanomaterials, University of Fribourg, 1700 Fribourg, Switzerland
7Japan Science and Technology Agency, Kawaguchi 332-0012, Japan

Received 23 October 2009; published 19 January 2010

We report spectroscopic ellipsometry measurements of the anisotropy of the interband transitions parallel and perpendicular to the planes of (LaTiO3)n(LaAlO3)5 multilayers with n=1–3. These provide direct information about the electronic structure of the two-dimensional (2D) 3d1 state of the Ti ions. In combination with local density approximation, including a Hubbard U calculation, we suggest that 2D confinement in the TiO2 slabs lifts the degeneracy of the t2g states leaving only the planar dxy orbitals occupied. We outline that these multilayers can serve as a model system for the study of the t2g 2D Hubbard model.

© 2010 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevLett.104.036401
DOI:
10.1103/PhysRevLett.104.036401
PACS:
71.27.+a, 73.21.Ac, 78.67.De, 78.67.Pt

*Current address: Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.

seos@ornl.gov

†Current address: Department of Physics, Columbia University, New York, NY 10027, USA.

‡Current address: Department of Physics, Pohang University of Science and Technology, Pohang, Kyungbuk 790-784, Korea.

§twnoh@snu.ac.kr

 
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