Resonant coherent quantum tunneling of the magnetization of spin-½ systems

B. Barbara

Yi-Hang Nie, J.-Q. Liang, Yunlong Shi +1 more

D. García-Pablos, N. Garcı́a, P. A. Serena +1 more

We investigate the reversal of magnetization and the coherence of tunneling when an external magnetic field is rotated instantaneously in systems of a few (N) spin 1/2 particles described by an anisotropic Heisenberg Hamiltonian at T=0. The temporal evolution is calculated by a numerically exact solution of the time-dependent Schrödinger equation, and the mean value in time of each spin component is computed as a function of the magnetic field. The correlation function and the spectrum are analyzed in terms of the macroscopic quantum coherence. Our calculations demonstrate that this model for small (N<11) magnetic particles exhibit collective tunneling of the magnetization only for some specific resonant values of the applied magnetic field, at variance with the Stoner–Wohlfarth model.

D. Galetti

Steven Tomsovic

Some general aspects of quantum tunnelling and coherence - application to the BEC atomic gases, A.J. Leggett tunnelling in two-dimensions, S.C. Creagh quantum environments - spin baths, oscillator baths and applications to quantum magnetism, P. Stamp coherent magnetic moment reversal in small particles with nuclear spins, A. Garg tunnelling from super- to normal-deformed minima in nuclei, T.L. Khoo solitons in the bose condensate, W.P. Reinhardt.

Luc Thomas, Frederic Lionti, A. Sulpice +4 more