TY - JOUR
T1 - In vacuo photoemission study of atomically controlled La1-x Srx Mn O3 thin films
T2 - Composition dependence of the electronic structure
AU - Horiba, K.
AU - Chikamatsu, A.
AU - Kumigashira, H.
AU - Oshima, M.
AU - Nakagawa, N.
AU - Lippmaa, M.
AU - Ono, K.
AU - Kawasaki, M.
AU - Koinuma, H.
PY - 2005
Y1 - 2005
N2 - We have investigated change in the electronic structures of atomically controlled La1-x Srx Mn O3 (LSMO) thin films as a function of hole-doping levels (x) in terms of in vacuo photoemission spectroscopy (PES) and x-ray absorption spectroscopy (XAS) measurements. The in vacuo PES measurements on a well-ordered surface of high-quality epitaxial LSMO thin films enable us to reveal their intrinsic electronic structures, especially the structure near the Fermi level (EF). We found that overall the features of the valence band as well as the core levels monotonically shifted toward lower binding energy as x was increased, indicating the systematic chemical-potential shift of LSMO thin films with hole doping. The peak nearest to EF due to the eg orbital is also found to move toward EF, while the peak intensity decreases with increasing x. The loss of spectral weight with x in the occupied density of states was compensated by the simultaneous increment of the shoulder structure in O 1s XAS spectra, suggesting the existence of a pseudogap, that is, a lowering in spectral weight at EF, for all metallic compositions. These results indicate that the simple rigid-band model does not describe the electronic structure near EF of LSMO, and that the spectral weight transfer from below to above EF across the gap dominates the spectral changes with x in LSMO thin films.
AB - We have investigated change in the electronic structures of atomically controlled La1-x Srx Mn O3 (LSMO) thin films as a function of hole-doping levels (x) in terms of in vacuo photoemission spectroscopy (PES) and x-ray absorption spectroscopy (XAS) measurements. The in vacuo PES measurements on a well-ordered surface of high-quality epitaxial LSMO thin films enable us to reveal their intrinsic electronic structures, especially the structure near the Fermi level (EF). We found that overall the features of the valence band as well as the core levels monotonically shifted toward lower binding energy as x was increased, indicating the systematic chemical-potential shift of LSMO thin films with hole doping. The peak nearest to EF due to the eg orbital is also found to move toward EF, while the peak intensity decreases with increasing x. The loss of spectral weight with x in the occupied density of states was compensated by the simultaneous increment of the shoulder structure in O 1s XAS spectra, suggesting the existence of a pseudogap, that is, a lowering in spectral weight at EF, for all metallic compositions. These results indicate that the simple rigid-band model does not describe the electronic structure near EF of LSMO, and that the spectral weight transfer from below to above EF across the gap dominates the spectral changes with x in LSMO thin films.
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U2 - 10.1103/PhysRevB.71.155420
DO - 10.1103/PhysRevB.71.155420
M3 - Article
AN - SCOPUS:28644440275
VL - 71
JO - Physical Review B - Condensed Matter and Materials Physics
JF - Physical Review B - Condensed Matter and Materials Physics
SN - 0163-1829
IS - 15
M1 - 155420
ER -