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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].…”

An optimal analytical expression for the superparamagnetic relaxation rate under conditions of a stochastic resonance for the model of bistable systems

“…To describe the dynamics of the magnetic moment, a rather simple model of discrete orientations [2,3] based on an analytical solution to the governing equation for the Kramers escape rates and a continuous model [4] based on a numerical solution to the Fokker-Planck equation with periodic drift components were used. The signal-to-noise ratio and the phase shift between the input and output signals were compared for the two models in [5]. The continuous model gave better results [6], but was rather cumbersome.…”

“…The frequency of attempts is of the order of the ferromagnetic resonance frequency and has a meaning of the transition rate of the magnetic moment vector in the absence of the potential barrier Kv. The discrete model with α 0 = const is a rough approximation, and a scaling factor should be introduced to adjust the dynamic susceptibility and the signal-to-noise ratio to their values obtained for the continuous model [5]. This enables one to use the results obtained for the discrete model in the simplest form for further calculations of related parameters.…”