Anomalous frequency dependence of ESR linewidths in TTF-TCNQ

Frequency dependence study of ESR linewidth in a well-studied 1-d system, TTF-TCNQ is reported. Such a technique is known to give useful information on charge carrier dynamics. Previously, NMR T1−1 versus frequency study on TTF-TCNQ has been reported and details of the electronic state were discussed by Soda et al. The present ESR data show a complete difference from them. Instead, an anomalous frequency dependence is observed; the ESR linewidth increases proportionally to ≈f2 at f<100 MHz and saturates above it. The temperature dependence of the amplitude of such anomaly behaves similar to that of CDW fluctuation, suggesting some relation between them.