Charge ordering and magnetopolarons in Na0.82CoO2.
Using spectral ellipsometry, we measured the dielectric function of a Na(0.82(2))CoO2 crystal that exhibits bulk antiferromagnetism with T(N)=19.8 K. We identify two prominent transitions as a function of temperature. The first one at 280 K involves marked changes of the electronic and lattice responses that are indicative of charge ordering in the CoO2 layers. The second transition occurs around T(N)=19.8 K and reveals sizable spin-charge coupling. The data are discussed in terms of charge ordering and formation of magnetopolarons due to a charge-induced spin-state transition of adjacent Co3+ ions.
Bernhard
C
C
Max-Planck-Institute for Solid State Research, Stuttgart, Germany.
Boris
A V
AV
Kovaleva
N N
NN
Khaliullin
G
G
Pimenov
A V
AV
Yu
Li
L
Chen
D P
DP
Lin
C T
CT
Keimer
B
B