相关论文: Evidence for two electronic components in NaxCoO2 …
To elucidate the low-energy excitation spectrum of correlated electrons on a 2D triangular lattice, we have studied the electrical resistance and specific heat down to 0.5 K and in magnetic fields up to 14 T, in NaxCoO2 samples with a Na…
We have performed specific heat and electric resistivity measurements of Na$_{x}$CoO$_{2}$ ($x=0.70$-0.78). Two anomalies have been observed in the specific heat data for $x=0.78$, corresponding to magnetic transitions at $T_{c}=22$ K and…
New electronic phases have been identified and placed in the (T,H) phase diagram of metallic NaxCoO2. At low Na-content (x = 0.36), the magnetic susceptibility diverges with a power law T^(-n), n<1, and shows (T,H) scaling, indicating the…
Results of thermo-electric power (S) and electrical resistivity (r) measurements are reported on NaxCoO2 compounds with x = 1.0, 0.7 and 0.6. These are single-phase compounds crystallizing in the hexagonal structure (space group P63/mmc) at…
We investigate the electronic states and the transport properties of the CoO2 plane in NaxCoO2 on the basis of the two-dimensional triangular lattice 11-band d-p model by using the fluctuation exchange approximation, where we consider the…
We report specific heat measurements down to 0.4 K on the layered oxide Na$_x$CoO$_2\cdot\it{y}$H$_2$O/D$_2$O with 0 $\le$ $\it{x}$ $\le$ 0.74 and $\it{y}$ = 0 and 1.4. For the nonhydrated system ($\it{y}$ = 0), the electronic specific heat…
Measurements of low temperature transport and thermodynamic properties have been used to characterize the non-Fermi liquid state of the itinerant ferromagnet ZrZn$_2$. We observe a $T^{5/3}$ temperature dependence of the electrical…
Electronic properties of the sodium cobaltate NaxCoO2 are systematically studied through a precise control of band filling. Resistivity, magnetic susceptibility and specific heat measurements are carried out on a series of high-quality…
Magnetic, transport, and specific heat measurements have been performed on layered metallic oxide Na$_{1.5}$Co$_2$O$_4$ as a function of temperature $T$. Below a characteristic temperature $T^*$=30$-$40 K, electrical resistivity shows a…
Using the merger of local density approximation and dynamical mean field theory, we show how electronic correlations increase the thermopower of Na$_{0.7}$CoO$_2$ by 200%. The newly revealed mechanism is an asymmetric shift of (quasi)…
Here we report an unconventional magnetic and transport phenomenon in a layered cobalt oxide, NaxCoO2. Only for x = 0.75, a magnetic transition of the second order was clearly detected at Tm ~ 22 K where an apparent specific-heat jump, an…
Specific heat of the layered NaxCoO2 (x=0.65, 0.70 and 0.75) oxides has been measured in the temperature range of 3-360 K and magnetic field of 0 and 9 T. The analysis of data, assuming the combined effect of inter-layer superexchange and…
We report measurement of room-temperature compressibility, thermal expansion, thermoelectric power a(T) at various pressures P < 20 kbar, basal-plane resistivity rab (T), magnetic susceptibility and thermal conductivity k(T) taken on…
We report results of specific heat measurements on polycrystalline samples of the layered superconductor, Na(0.3)CoO(2).1.3H(2)O. The electronic contribution to the specific heat, gamma, is found to be 12.2 mJ/mol-K2. The feature at the…
The low magnetic field diffusion thermopower of a high mobility GaAs-heterostructure has been measured directly on an electrostatically defined micron-scale Hall-bar structure at low temperature (T = 1.6 K) in the low magnetic field regime…
We find that the heat capacity of a strongly correlated metal presents striking changes with respect to Landau Fermi liquid theory. In contrast with normal metals, where the electronic specific heat is linear at low temperature (with a T^3…
An antiferromagnetic transition is observed in single crystal EuRh2As2 at a high temperature T_N = 47 K compared to the ferromagnetic Weiss temperature theta = 12 K. We show that this is, surprisingly, consistent with mean field theory. A…
Comprehensive low-temperature specific heat data C(T,H) of Na_0.35CoO2-1.3H_2O with temperature T down to 0.6 K and the magnetic field H up to 8 T are presented. For the normal state, the values of gamma_n=13.94 mJ/mol K2, and Debye…
For the thermoelectric properties of NaxCoO2, we analyze the effect of local Coulomb interaction and (disordered) potential differences for Co-sites with adjacent Na-ion or vacancy. The disorder potential alone increases the resistivity and…
A 59Co NMR study of CoO2, the x=0 end member of AxCoO2 (A = Na, Li...) cobaltates, reveals a metallic ground state, though with clear signs of strong electron correlations: low-energy spin fluctuations develop at wave vectors q different…