Spin-controlled Mott-Hubbard bands in LaMnO3 probed by optical ellipsometry.
Spectral ellipsometry is used to determine the dielectric function of an untwinned crystal of LaMnO3 in the range 0.5-5.6 eV at temperatures 50<or=T<or=300 K. A pronounced redistribution of spectral weight is found at the Ne el temperature T(N)=140 K. The anisotropy of the spectral weight transfer matches the magnetic ordering pattern. A superexchange model quantitatively describes spectral weight transfer induced by spin correlations. This analysis implies that the lowest-energy transitions around 2 eV are intersite d-d transitions, and that LaMnO3 is a Mott-Hubbard insulator.
Kovaleva
N N
NN
Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany.
Boris
A V
AV
Bernhard
C
C
Kulakov
A
A
Pimenov
A
A
Balbashov
A M
AM
Khaliullin
G
G
Keimer
B
B