Giant electron-electron scattering in the Fermi-liquid state of Na0.7CoO2.
The in-plane resistivity rho and thermal conductivity kappa of single crystal Na0.7CoO2 were measured down to 40 mK. Verification of the Wiedemann-Franz law, kappa/T=L(0)/rho as T-->0, and observation of a T2 dependence of rho at low temperature establish the existence of a well-defined Fermi-liquid state. The measured value of coefficient A reveals enormous electron-electron scattering, characterized by the largest Kadowaki-Woods ratio A/gamma(2) encountered in any material. The rapid suppression of A with magnetic field suggests a possible proximity to a magnetic quantum critical point. We also speculate on the possible role of magnetic frustration and proximity to a Mott insulator.
Département de physique, Université de Sherbrooke, Sherbrooke, Québec, Canada.
S Y
SY
Li
Louis
L
Taillefer
D G
DG
Hawthorn
M A
MA
Tanatar
Johnpierre
J
Paglione
M
M
Sutherland
R W
RW
Hill
C H
CH
Wang
X H
XH
Chen