Electron and orbital correlations in Ca2-xSrxRuO4 probed by optical spectroscopy.
The optical conductivity spectra of the quasi-two-dimensional Ca2-xSrxRuO4 (0.0< or =x< or =2.0) system were investigated. In the Mott insulating state, two electron correlation-induced peaks were observed about 1.0 and 1.9 eV, which could be explained using the 3-orbital Hubbard model. The low frequency peak showed a shift toward higher frequency as temperature was lowered, indicating that electron-phonon interactions play an important role in the orbital arrangements. From the systematic analysis, it was suggested that the antiferro-orbital and the ferro-orbital ordering states could coexist.
Lee
J S
JS
School of Physics and Research Center for Oxide Electronics, Seoul National University, Korea.
Lee
Y S
YS
Noh
T W
TW
Oh
S-J
SJ
Yu
Jaejun
J
Nakatsuji
S
S
Fukazawa
H
H
Maeno
Y
Y