EPR Relaxation and Transport Phenomena in the Quasi-One-Dimensional Conductor β-NaxV2O5

The dynamical behaviors of the 3 d -electrons in β-Na x V 2 O 5 are studied by means of EPR relaxation, in the temperature range between 19 and 303 K. The anisotropy and the temperature dependence of the linewidth are found to originate mainly from the dipolar interaction between the 3 d -electrons of the excited state of the bipolaron at the V 1 site and the delocalized dilute paramagnetic state at the V 3 site. The correlation time of the fluctuating local field is estimated to be of the order of 10 -11 s. On the basis of this correlation time, the transverse conductivity is found in terms of the diffusive electron hopping motion between the V 1 and V 3 sites perpendicular to the chain axis, while the longitudinal one is interpreted as the collective motion of the bipolaron parallel to the chain axis.