Charge ordering, commensurability, and metallicity in the phase diagram of the layered NaxCoO2.
The phase diagram of nonhydrated NaxCoO2 has been determined by changing the Na content x using a series of chemical reactions. As x increases from 0.3, the ground state goes from a paramagnetic metal to a charge-ordered insulator (at x=1/2), then to a "Curie-Weiss metal" (around 0.70), and finally to a weak-moment magnetically ordered state (x>0.75). The unusual properties of the state at 1/2 (including particle-hole symmetry at low T and enhanced thermal conductivity) are described. The strong coupling between the Na ions and the holes is emphasized.
Foo
Maw Lin
ML
Department of Chemistry, Princeton University, New Jersey 08544, USA.
Wang
Yayu
Y
Watauchi
Satoshi
S
Zandbergen
H W
HW
He
Tao
T
Cava
R J
RJ
Ong
N P
NP