UNIVERSAL CRITICAL SCALING OF DC AND AC COMPLEX RESISTIVITIES IN AN INDIUM FILM NEAR THE VORTEX-GLASS TRANSITION

We have made ac complex resistivity measurements from 100 Hz to 5 MHz in the linear regime, as well as de resistivity measurements, for a th ick indium film in constant magnetic fields B. At B = 0.1 T, the vorte x-glass transition temperature T-g can be defined from the frequency-i ndependent phase of the ac resistivity, which is in good accordance wi th the value determined independently from de measurements. Critical e xponents (v similar to 1.4, z similar to 8) extracted from both de and ac measurements are consistent. In addition to the vortex-correlation length xi(g)(T), the vortex-relaxation time tau(g)(T) is directly obt ained from the frequency dependence of the ac resistivity. Within a li mited critical regime (\T-T-g\ similar to>0.1 K) about the phase trans ition, the amplitude and phase of the ac resistivity as well as the de resistivity follow the universal scaling functions, which resemble th ose found in YBa2Cu3O7. In B=1 T, we have observed the similar scaling behavior for the de resistivity to that in B=0.1 T, whereas degradati on of the scaled isotherms is visible for the ac resistivity. Although this problem still awaits further studies, all of these findings offe r strong experimental evidence for the second-order transition in indi um films.