Propagation of Magnetic Avalanches in Mn12Ac at High Field Sweep Rates

Abstract

Time-resolved measurements of the magnetization reversal in single crystals of Mn 12 Ac in pulsed magnetic fields, at magnetic field sweep rates from 1.5 kT / s up to 7 kT / s , suggest a new process that cannot be scaled onto a deflagrationlike propagation driven by heat diffusion. The sweep rate dependence of the propagation velocity, increasing from a few 100 m / s up to the speed of sound in Mn 12 Ac , indicates the existence of two new regimes at the highest sweep rates, with a transition around 4 kT / s that can be understood as a magnetic deflagration-to-detonation transition.