Nuclear magnetic resonace sNMRd, EPR and magnetization measurements in NaxCoO2 for 0.65<x<0.75 are presented. While the EPR signal arises from Co4+ magnetic moments ordering at Tc.26 K, 59Co NMR signal originates from cobalt nuclei in metallic regions with no long range magnetic order and characterized by a generalized susceptibility typical of strongly correlated metallic systems. This phase separation in metallic and magnetic insulating regions is argued to occur below T*(x) (220–270 K). Above T* an anomalous decrease in the intensity of the EPR signal is observed and associated with the delocalization of the electrons which for T<T* were localized on Co4+ dz2 orbitals. It is pointed out that the in-plane antiferromagnetic coupling J <<T* cannot be the driving force for the phase separation.
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