Tuning magnetization avalanches in Mn$_{12}$-acetate*

We report the results of a systematic study of magnetic avalanches (abrupt magnetization reversals) in the molecular magnet Mn$_{12}$-acetate using a micron-sized Hall sensor array. Measurements were taken for: (a) fixed magnetic field (constant barrier against spin reversal); and (b) fixed energy release obtained by adjusting the barrier and $\Delta M$. A detailed comparison with the theory of magnetic deflagration of Garanin and Chudnovsky [1] will be presented and discussed. [1] D. A. Garanin and E. M. Chudnovsky, Phys. Rev. B 76, 054410 (2007)