Scaling behavior and estimation of activation energy of polycrystalline RuSr2GdCu2O8 superconductor from AC susceptibility measurements

Abstract

In this study, the measured curves of AC susceptibility (ACS) components, χ′(T) and χ″(T), of polycrystalline RuSr2GdCu2O8 (Ru-1212) superconductor were scaled onto a single curve using the peak temperature of its imaginary part (Tp) as the scaling parameter for various AC field amplitudes from 0.5 to 24 G. The dependence of the AC magnetic field amplitude on Tp is scaled as: Hac ∼ (1−Tp/Tc)2.25. Similarly, the current density Jc, extracted from the AC field amplitude is also scaled as: Jc ∼ (1 − Tp/Tc)2.25. The dependencies of Tp on frequency and AC field amplitude are also investigated and the time parameter t0 of the order of 10−8 s is estimated from the dependence of Tp on frequency. The dependencies of activation energy on temperature, T, and the field amplitude, Hac, are obtained from the Arrhenius-like semilog plot of frequency (ν) and Tp. Such dependencies on temperature and field amplitude can be described by a scaling law of the form: U(Hac,T) = U0[1 − T/Tp]Hac−0.17.