Dynamics of magnetic nano particles in a viscous fluid driven by rotating magnetic fields

Abstract

The rotational dynamics of magnetic nano particles in rotating magnetic fields in the presence of thermal noise is studied both theoretically and by performing numerical calculations. Kinetic equations for the dynamics of particles with uniaxial magnetic anisotropy are studied and the phase lag between the rotating magnetic moment and the driving field is obtained. It is shown that for large enough anisotropy energy the magnetic moment is locked to the anisotropy axis so that the particle behaves like a rotating magnetic dipole. The corresponding rigid dipole model is analyzed both numerically by solving the appropriate Fokker-Planck equation and analytically by applying an effective field method. In the special case of a rotating magnetic field applied analytic results are obtained in perfect agreement with numerical results based on the Fokker-Planck equation. The analytic formulas derived are not restricted to small magnetic fields or low frequencies and are therefore important for applications. The illustrative numerical calculations presented are performed for magnetic parameters typical for iron oxide.

References in corpus (3)

• Fokker-Planck and Landau-Lifshitz-Bloch Equations for Classical Ferromagnets
• Dynamics of magnetic single domain particles embedded in a viscous liquid
• Rotational properties of ferromagnetic nanoparticles driven by a precessing magnetic field in a viscous fluid

Cited by in corpus (11)

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• Drift of suspended single-domain nanoparticles in a harmonically oscillating gradient magnetic field
• Dynamics and Energy Dissipation of a Rigid Dipole Driven by the RF-field in a Viscous Fluid: Deterministic Approach
• Including nanoparticle shape into macrospin models
• Numerical Analysis of the Nanoparticle Dynamics in a Viscous Liquid: Deterministic Approach