FREQUENCY-DEPENDENCE OF THE VORTEX-STATE RESISTIVITY IN YBA2CU3O7-DELTA

Swept-frequency measurements 1-600 MHz) of the vortex resistivity in YBa2Cu3O7 were performed in fields from 0.5 to 8 T. At all fields studied, both the real and imaginary parts of the resistivity display a power-law frequency dependence with exponents alpha1 and alpha2 that depend only on the reduced field h=H/H* (T). The scaling field H* (T) is identified with the critical field for the solid-to-liquid transition. The power-law dependence and the frequency variation of the phase angle are consistent with the model of Fisher, Fisher, and Huse. The field dependence of alpha1 and alpha2 provides an improved determination of the critical phase angle (65.7-degrees) and the dynamic exponent z (3.7).