Studies of vortex dynamics in HTS and conventional amorphous superconductors using a sapphire ring resonator

Abstract

Vortex critical dynamics of superconducting amorphous m03si films are investigated at microwave frequencies from 8 to 19 GHz by using a high-Q sapphire ring resonator at the whispering gallery (WG) modes. It is found that the microwave surface resistance Rs in the vortex-state of α-m03si follows the scaling relation Rs ∼ δν(z-1/2)R̄s(f̄), where δ = |1 - (T/Tm)|, Tm(H) is the vortex-glass melting temperature in a constant magnetic field H, R̄s is a scaling function, f̄ = fδ-νz, and ν ≈ 2/3, z ≈ 3.0 are the static and dynamics exponents associated with the vortexglass transition1,2. In contrast, the vortex dynamics at microwave frequencies for high-temperature superconductors (HTS) such as Nd1.85Ce0.15CuO4 and YBa2Cu3O7 is associated with vortex depinning and diffusion1,2,3 rather than the critical dynamics of the vortex-glass transition1,2. Physical quantities associated with the viscous motion of vortex-liquid in high-temperature superconductors are derived from the microwave measurements.