Evidence of rf-driven branching of dendritic vortex avalanches in MgB2 microwave resonators

TL;DR

This paper investigates how dendritic flux avalanches in MgB2 superconducting films affect microwave response, revealing vortex avalanches and dendrite branching through experimental and simulation comparisons.

Contribution

It demonstrates the influence of dendritic flux avalanches on microwave properties and confirms the branching behavior via experimental data and molecular dynamics simulations.

Findings

Resonance curve jumps indicate vortex avalanches

Dendrite branching occurs due to microwave current shaking

Avalanche-size distributions match simulations

Abstract

The influence of dendritic magnetic-flux penetration on the microwave response of superconducting MgB2 films is investigated by a coplanar resonator technique. The peculiar feature consists of jumps in the resonance curve, induced by vortex avalanches freezing flux inside the resonator. Due to a shaking effect, microwave currents maintain the vortex system close to a nonequilibrium state, resulting in dendrite branching. Avalanche-size distributions before and after flux-pinning tailoring by heavy-ion irradiation are fully consistent with molecular dynamics simulations reported in literature.