  We found a new cobalt oxide (CaOH)1.14CoO2 by utilizing the high-pressure
technique. X-ray and electron diffraction studies revealed that the compound
has layer structure which consists of CdI2-type CoO2 layers and rock-salt-type
double CaOH atomic layers. The two subcells have incommensurate periodicity
along the a-axis, resulting in modulated crystal structure due to the
inter-subcell interaction. The structural modulation affects carrier conduction
through the potential randomness. We found that the two-dimensional (2-D)
variable-range hopping (VRH) regime with hole conduction is dominant at low
temperature for this compound, and that the conduction mechanism undergoes
crossover from the 2-D VRH regime to thermal activation-energy type one with
increasing temperature. Based on the experimental results of resistivity,
thermoelectric power, magnetic susceptibility and specific heat measurements,
we suggested a possible electronic-band structure model to explain these
results. The cobalt t2g-derivative band crosses Fermi energy level near the
band edge, yielding small finite density of localized states at the Fermi level
in the band. The observed resistivity, Seebeck coefficient, large Pauli
paramagnetic component in the magnetic susceptibility and comparatively small
Sommerfeld constant in the specific heat are principally attributed to the
holes in the t2g-derivative band. We estimated the Wilson ratio to be about
2.8, suggesting the strong electron correlation realized in this compound.
