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Phys. Rev. Lett. 97, 057601 (2006) [4 pages]

Photoemission from Buried Interfaces in SrTiO3/LaTiO3 Superlattices

M. Takizawa,1 H. Wadati,1 K. Tanaka,1 M. Hashimoto,1 T. Yoshida,1 A. Fujimori,1 A. Chikamatsu,2 H. Kumigashira,2 M. Oshima,2 K. Shibuya,3 T. Mihara,4 T. Ohnishi,3 M. Lippmaa,3 M. Kawasaki,5 H. Koinuma,4 S. Okamoto,6 and A. J. Millis6
1Department of Physics and Department of Complexity Science and Engineering, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwashi, Chiba, 277-8561, Japan
2Department of Applied Chemistry, University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan
3Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwashi, Chiba, 277-8581, Japan
4Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama, Kanagawa, 226-8503, Japan
5Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi, 980-8577, Japan
6Department of Physics, Columbia University, 538 West 120th Street, New York, New York 10027, USA
Received 7 April 2006; published 1 August 2006

We have measured photoemission spectra of SrTiO3/LaTiO3 superlattices with a topmost SrTiO3 layer of variable thickness. A finite coherent spectral weight with a clear Fermi cutoff was observed at chemically abrupt SrTiO3/LaTiO3 interfaces, indicating that an "electronic reconstruction" occurs at the interface between the Mott insulator LaTiO3 and the band insulator SrTiO3. For SrTiO3/LaTiO3 interfaces annealed at high temperatures (~1000 °C), which leads to Sr/La atomic interdiffusion and hence to the formation of La1-xSrxTiO3-like material, the intensity of the incoherent part was found to be dramatically reduced whereas the coherent part with a sharp Fermi cutoff was enhanced due to the spread of charge. These important experimental features are well reproduced by layer dynamical-mean-field-theory calculation.

©2006 The American Physical Society

URL: http://link.aps.org/doi/10.1103/PhysRevLett.97.057601
DOI: 10.1103/PhysRevLett.97.057601
PACS: 79.60.Jv; 71.27.+a; 73.20.-r; 78.67.Pt
  • 79.60.Jv
    Photoelectron spectra of interfaces; heterostructures; nanostructures
  • 71.27.+a
    Strongly correlated electron systems; heavy fermions
  • 73.20.-r
    Electron states at surfaces and interfaces
  • 78.67.Pt
    Optical properties of multilayers and superlattices
  • YEAR: 2006

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