Photoemission from buried interfaces in SrTiO3/LaTiO3 superlattices.
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 (approximately 1000 degrees C), which leads to Sr/La atomic interdiffusion and hence to the formation of La(1-x)Sr(x)TiO3-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.
Takizawa
M
M
Department of Physics and Department of Complexity Science and Engineering, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwashi, Chiba 277-8561, Japan.
Wadati
H
H
Tanaka
K
K
Hashimoto
M
M
Yoshida
T
T
Fujimori
A
A
Chikamatsu
A
A
Kumigashira
H
H
Oshima
M
M
Shibuya
K
K
Mihara
T
T
Ohnishi
T
T
Lippmaa
M
M
Kawasaki
M
M
Koinuma
H
H
Okamoto
S
S
Millis
A J
AJ