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Abstract: We have studied the crystal structure and transport properties of the new cobalt oxide (CaOH)1.14CoO2. The compound has the 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 a 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-type hole conduction is dominant at low temperature. [Copyright &y& Elsevier]

Abstract: We report on the result of muon spin relaxation measurements in a deuterated specimen of cobalt oxyhydrate superconductor, , which exhibits a hysteresis resembling ferromagnetic order in magnetic susceptibility. While the possibility of bulk ferromagnetic order is eliminated by the absence of spontaneous muon precession signal under zero field, the spectra indicate the appearance of magnetic domains below in accordance with a hysteresis in the susceptibility. This correlation demonstrates strong coupling between the water layers and the electronic state of CoO2 layers. [Copyright &y& Elsevier]