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Abstract:
An in-plane Kondo-like resistivity minimum is found with a corresponding temperature T-min, around 7 K for hydrated Na0.23CoO2 single crystals. Below 7 K, the resistivity exhibits logarithmic temperature dependence of alpha lnT, where alpha is independent of the external magnetic field up to 8 T. The feature is resulted in terms of the Kondo-like effect arising from the presence of spin disorder induced by water intercalation in the a-b plane. Our results indicate that the water intercalation weakens the coupling between the CoO2 layers and increases the two-dimensional characteristic of transport properties. The dependence of resistivity minimum on applied field proved also the suppression of localized Co(1) site on paramagnetic triangular superlattice. Further, the present experiments give the evidence of a more complex cooperative phenomena involving charge or spin ordering in the CoO2 layers as a dominating factor for the understanding of hydrated NaxCoO2 compounds. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4772620]
