Nonlinear response of superparamagnets with finite damping: an analytical approach

Abstract

The strongly damping-dependent nonlinear dynamical response of classical superparamagnets is investigated by means of an analytical approach. Using rigorous balance equations for the spin occupation numbers a simple approximate expression is derived for the nonlinear susceptibility. The results are in good agreement with those obtained from the exact (continued-fraction) solution of the Fokker-Planck equation. The formula obtained could be of assistance in the modelling of the experimental data and the determination of the damping coefficient in superparamagnets.

7 PR pages, 2 figures

References in corpus (5)

• Thermally activated escape rates of uniaxial spin systems with transverse field
• Nonlinear dynamic susceptibilities of interacting and noninteracting nanoparticle systems
• Relaxation time of weakly interacting superparamagnets
• Thermodynamic perturbation theory for dipolar superparamagnets
• Linear and nonlinear superparamagnetic relaxation at high anisotropy barriers

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• Quantum and statistical mechanics in open systems: theory and examples