J. Phys. I France
Volume 1, Numéro 7, July 1991
Page(s) 1019 - 1028
DOI: 10.1051/jp1:1991186
J. Phys. I France 1 (1991) 1019-1028

The thermoactivation rate of charged particles in a magnetic field

D. A. Garanin

Moscow Institute of Radio Engineering, Electronics and Automation, 117454, Moscow, Prospect Vernadskogo 78, U.S.S.R.

(Received 19 November 1990, revised 5 March 1991, accepted 11 March 1991)

We consider a diffusion of a charged particle over a three-dimensional barrier in a magnetic field. By the solution of the Fokker-Planck equation it is shown that the magnetic field causes the diminishing of the pre-factor $\Gamma_0$ in the expression for the particle's thermoactivation rate: $\Gamma=\Gamma_0 \exp(-U_0/T)$, $T\ll U_0$. Unlike the two-dimensional case considered earlier [3, 4], in the general situation this diminishing is non-uniform with respect to the orientation of the vector B, with a saturation at some non-zero level for some range of orientations. The latter causes the splitting of the relaxation peak in the bulk materials containing randomly oriented two-well relaxators at high magnetic fields.

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