Avalanche-like vortex penetration driven by pulsed microwave fields in an epitaxial LaSrCuO thin film

Abstract

Different vortex penetration regimes have been registered in the output voltage signal of a magnetometer when single microwave pulses are applied to an epitaxial overdoped La 2Àx Sr x CuO 4 thin film in a perpendicular dc magnetic field. The onset of a significant variation in the sample magnetization which exists below threshold values of temperature, dc magnetic field, and pulse duration is interpreted as an avalanche-type flux penetration. The microwave contribution to the background electric field suggests that the nucleation of this fast vortex motion is of electric origin, which also guarantees the occurrence of vortex instabilities under adiabatic conditions via the enhancement of the flux flow resistivity. Flux creep phenomena and heat transfer effects act as stabilizing factors against the microwave-pulse-induced fast flux diffusion. V C 2013 AIP Publishing LLC. [http://dx

Thermally Driven Inhibition of Superconducting Vortex Avalanches

“…According to the model based on thermomagnetic instabilities [12], an avalanche is triggered by a thermal fluctuation (hot spot), which facilitates more flux motion toward the hot place, with a subsequent heat release. Under quasi-equilibrium conditions, the avalanches can also be triggered by microwave pulses [13,14] or AC signals at near resonant frequencies of superconducting cavities [1]. The situation is somewhat different with a broadband microwave (mw) field sweep, with avalanches triggered at different depinning frequencies due complicated local vortex pinning potentials [15].…”

Fast dynamics of vortices in superconductors

“…According to the model based on thermomagnetic instabilities [188], an avalanche is triggered by a thermal fluctuation (hot spot), which facilitates more flux motion toward the hot place, with a subsequent heat release. Under quasiequilibrium conditions, the avalanches can also be triggered by microwave pulses [189] or ac signals at near resonant frequencies of superconducting cavities [190]. Under a broadband microwave field sweep, flux avalanches are triggered at different depinning frequencies due the distribution in strength of individual vortex pinning sites [191].…”