Josephson vortex dynamic in superconducting $YBa_2Cu_3O_x$ ceramics

TL;DR

This study investigates the dynamic behavior of Josephson vortices in YBa2Cu3O_x ceramics under low-frequency ac magnetic fields, revealing complex frequency-dependent responses and suggesting vortex volume changes during motion.

Contribution

It provides new insights into Josephson vortex dynamics in high-temperature superconductors through low-frequency ac susceptibility measurements.

Findings

Complex frequency dependence of ac magnetic response observed.

Evidence suggests Josephson vortex volume increases during movement.

Interactions between vortices influence the observed behavior.

Abstract

The Josephson vortices dynamic in superconducting $YBa_2Cu_3O_x$ ceramics was studied in frequency range 0.01-0.5 Hz by ac susceptibility measurements in non complete magnetic flux penetration regime. We have found that with the increase of magnetic field frequency starting from 0.01 Hz the ac magnetic response shows complex frequency dependence: in one half period of a sinusoidal field appear two asymmetrical peaks of real $\Delta\chi\prime$ and imaginary $\chi\prime\prime$ parts of the ac susceptibility. The analysis of experimental results has led to an idea that probably the volume (diameter) of Josephson vortices increases during its movement. The experimental results are discussed in terms of Josephson vortex - vortex interactions.