Forced Precession of a Ferromagnetic Nanoparticle with a Finite Anisotropy Suspended in a Liquid: Nonlinear Aspects

Authors T.V. Lyutyy , V.V. Reva , N.S. Petrenko, M.O.Pavlyuk

Sumy State University, 2, Rimsky-Korsakov St., 40007 Sumy, Ukraine

Issue Volume 11, Year 2019, Number 5
Dates Received 11 September 2019; revised manuscript received 08 October 2019; published online 25 October 2019
Citation T.V. Lyutyy, V.V. Reva, N.S. Petrenko, M.O.Pavlyuk, J. Nano- Electron. Phys. 11 No 5, 05021 (2019)
PACS Number(s) 05.45. – a, 47.65.Cb, 75.50.Mm, 82.70. – y
Keywords Ferrofluid, Ferromagnetic nanoparticle, Finite anisotropy, Coupled motion, Uniform precession, Nonuniform precession, Chaotic dynamics.

The coupling between mechanical rotation and internal magnetic dynamics of each nanoparticle is an important point of the microscopic description of a ferrofluid interacting with an external field. Here, based on classical equations the deterministic case of the forced coupled precession is described numerically. Our main aim is to study the stable prerecession regimes, which are generated by a rotating external field. In addition to the well-known uniform precession motion, a few nonlinear regimes are observed and discussed. One of them is a nonuniform precession, which was described earlier for the case of an immobilized nanoparticle, where the particle is supposed to be fixed in a solid matrix, and for the case of a rigid dipole, where the nanoparticle magnetization is supposed to be locked in the crystal lattice due to the high anisotropy. Then, the finite anisotropy gives an additional degree of freedom that leads to the generation of the chaotic regime, and one more deterministic regime, which is characterized by oscillations performed synchronously with the external field. A deep understanding of the motion character allows to take control over the heating process in hyperthermia method for cancer treatment. In particular, now it is clear why even a slight tuning of the field frequency can lead to nonlinear growth of the heating rate.

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