Magnetic Detonation in Crystals of Nanomagnetics

Presently, there is much interest in molecular (nano)magnets with unique superparamagnetic properties, which may be used for quantum computing and memory storage [1-4]. A remarkable feature of nanomagnets is that these macromolecules with large effective molecular spin (e.g., S = 10 for Mn12acetate) can keep their spin orientation upon the reversal of the external magnetic field [3,4]. Because of the strong molecular anisotropy, the spin of a nanomagnet is directed preferentially along the so-called easy axis of the crystal, and it leads to a considerable energy barrier between the spin-up and spin-down states. At low temperatures, in a magnetic field directed along the easy axis, the states with spin along the field and against the field become stable and metastable, respectively. The energy difference between the two states is determined by the Zeeman energy Q, as illustrated in Fig. 1, with the energy barrier designated by Ea. The barrier hinders spontaneous transition from the metastable to stable state at low temperatures [4,5], so that fast spin flipping requires help from outside.