Butterfly hysteresis loop and dissipative spin reversal in the S = 1/2, V-15 molecular complex

Chiorescu I, Wernsdorfer W, Müller A, Bögge H, Barbara B. Butterfly hysteresis loop and dissipative spin reversal in the S = 1/2, V-15 molecular complex. PHYSICAL REVIEW LETTERS. 2000;84(15):3454-3457.Time resolved magnetization measurements have been performed on a spin 1/2 molecular complex, so-called V-15. Despite the absence of a barrier, magnetic hysteresis is observed over a time scale of several seconds. A detailed analysis in terms of a dissipative two-level model is given, in which fluctuations and splittings are of the same energy. Spin-phonon coupling leads to long relaxation times and to a particular "butterfly" hysteresis loop