Fermi surface and quasiparticle dynamics of Na0.7CoO2 investigated by angle-resolved photoemission spectroscopy.
We present the first angle-resolved photoemission study of Na0.7CoO2, the host material of the superconducting NaxCoO2.nH(2)O series. Our results show a hole-type Fermi surface, a strongly renormalized quasiparticle band, a small Fermi velocity, and a large Hubbard U. The quasiparticle band crosses the Fermi level from M toward Gamma suggesting a negative sign of effective single-particle hopping t(eff) (about 10 meV) which is on the order of magnetic exchange coupling J in this system. Quasiparticles are well defined only in the T-linear resistivity (non-Fermi-liquid) regime. Unusually small single-particle hopping and unconventional quasiparticle dynamics may have implications for understanding the phase of matter realized in this new class of a strongly interacting quantum system.
Hasan
M Z
MZ
Joseph Henry Laboratories, Department of Physics, Princeton University, Princeton, New Jersey 08544, USA. mzhasan@Princeton.edu
Chuang
Y-D
YD
Qian
D
D
Li
Y W
YW
Kong
Y
Y
Kuprin
A
A
Fedorov
A V
AV
Kimmerling
R
R
Rotenberg
E
E
Rossnagel
K
K
Hussain
Z
Z
Koh
H
H
Rogado
N S
NS
Foo
M L
ML
Cava
R J
RJ