Vortex dynamics driven by AC magnetic field in YBCO thin films with complex pinning structures

Abstract

We investigated the AC magnetic response of a YBa 2 Cu 3 O 7 film with embedded BaZrO 3 nanorods and Y 2 O 3 nanoparticles at a static magnetic field H dc lower than the matching field H Φ. We proposed a practical formula for the determination of the induced current J during AC susceptibility measurements, which allows us to directly obtain the pinning potential U c from the characteristics of electric field E versus J. We show that the dynamic critical current J d induced at the depinning frequency f d can be experimentally obtained by measuring m′(T) and m″(T) at different frequencies and amplitudes. It was found that the value of f d obtained by extrapolation of J to J d in the PHz domain is much higher than the frequency reported for ordinary YBa 2 Cu 3 O 7 thin films as determined by microwave impedance measurements.AC susceptibility, vortex dynamics, pinning energy, depinning frequency, dynamic critical current, microwave impedance measurements

Review on Microwave Surface Resistance of High Temperature Superconductor Yttrium Barium Copper Oxide

“…Vortex motion in YBCO generates a substantial amount of energy dissipation, which greatly impacts its microwave surface resistance, especially under high magnetic field conditions. Controlling and limiting vortex motion is crucial for decreasing microwave surface resistance in practical uses of YBCO superconductors [36].…”

Vortex pinning properties at dc and microwave frequencies of YBa2Cu3O7-x films with nanorods and nanoparticles

“…The broad range of frequencies at which HTS wires need to operate in the various applications (from dc in magnets to GHz in cavities), requires the characterization of the nanostructured films under different dynamic vortex regimes. Ac susceptibility measurements have been used to provide insights into the vortex dynamics of YBCO nanocomposites [39] in various regimes, from high [40] to low ac amplitudes [41], at frequencies up to 10 kHz. On the other hand, surface impedance measurements at microwave (MW) frequencies (at ca.…”