Stochastic resonance in low-disperse magnets: Mechanism of subbarrier magnetization reversal

Effect of an arbitrarily directed permanent magnetic field on the dynamic susceptibility of a superparamagnetic particle under the conditions of stochastic resonance

“…Small magnetic particles of this type having nanometer sizes, which possess unique properties, have been of interest to researchers, especially during the last decade, both in the fundamental and in the applied aspect. The previous work that considered the phenomenon of stochastic resonance for disperse single-axis particles for the superbarrier [3,4] and the subbarrier mechanism of magnetic reversal [5,6] showed the presence of a characteristic nonmonotonic dependence of the response of the system to a weak alternating field to the intensity of internal noise of thermal or quantum nature. The values of the components of the dynamic magnetic susceptibility and of the signal-to-noise ratio, obtained in the approximation of two states for single-domain particles under the conditions of stochastic resonance, were confirmed by numerical calculations based on the solution of the Fokker-Planck equation by the method of chain matrix fractions [7,8].…”

On the simulation of the Brownian motion of a domain wall in nanowires

“…Traditionally, the fluctuation behavior has been investigated taking into account the thermally acti vated and tunneling magnetization reversal processes [2,3]. The domain wall motion stimulated by thermal fluctuations occurs in a wide temperature range [4], whereas the effect of quantum tunneling through the energy barrier becomes significant only at low temper atures [5,6] and in very thin wires.…”

“…Taking into account expression (1), the force of interaction of the domain wall with anisotropy inho mogeneities can be written as (2) Since the domain wall covers a large number of crystallites, the force profile F(z) is statistically univer sal: in accordance with the central limit theorem [13], it is described by a Gaussian random function [12]. It should be noted that magnetic inhomogeneities can be of any type (not necessarily fluctuating directions of the local anisotropy axes).…”