Magnetic instability of MgB2 thin film triggered by the various sweeping rates of an applied magnetic field.

Up to now, the vortex avalanche is known to depend critically on the changing of some external parameters, such as the applied magnetic field, the temperature, and the demagnetization factor. In this study, we found the sweeping rate (SR) of the applied magnetic field to be another parameter that contributed to the appearance of the vortex avalanche. For example, a fast SR 500 Oe/s enhanced the vortex avalanche quietly compared to the case of a slow SR of 3 Oe/s. The dependence of the appearance of the vortex avalanche on the SR was quite strong, especially at low temperatures. A H-T phase diagram that distinguishes the regions of magnetic stability and instability is drawn for each SR. [ABSTRACT FROM AUTHOR]