Thermally-assisted tunnelling of magnetization in (Mn_0.96Cr_0.04)₁₂-ac

The thermally assisted resonant tunnelling in a single crystal (Mn_0.96Cr_0.04)12-ac is studied in this paper. The obtained hysteresis loops at seven different temperatures between 1.8 and 3K show obvious dependence on temperature. The magnetization steps occur at specific field values of nH_\rm R with H_\rm R≈0.46T, which are approximately independent of the temperature. As the temperature decreases, the area enclosed in the hysteresis loops and the actual number n of the resonances increase, which provides clear evidence of thermally assisted resonant tunnelling in (Mn_0.96Cr_0.04)12-ac.