Nándori I, Rácz J
MTA-DE Particle Physics Research Group, H-4010 Debrecen PO Box 105, Hungary and Institute of Nuclear Research, PO Box 51, H-4001 Debrecen, Hungary.
Phys Rev E Stat Nonlin Soft Matter Phys. 2012 Dec;86(6 Pt 1):061404. doi: 10.1103/PhysRevE.86.061404. Epub 2012 Dec 11.
The deterministic Landau-Lifshitz-Gilbert equation has been used to investigate the nonlinear dynamics of magnetization and the specific power loss in magnetic nanoparticles with uniaxial anisotropy driven by a rotating magnetic field, generalizing the results obtained for the isotropic case found by P. F. de Châtel, I. Nándori, J. Hakl, S. Mészáros, and K. Vad [J. Phys. Condens. Matter 21, 124202 (2009)]. As opposed to many applications of magnetization reversal in single-domain ferromagnetic particles, where losses must be minimized, in this paper, we study the mechanisms of dissipation used in cancer therapy by hyperthermia, which requires the enhancement of energy losses. We show that for circularly polarized field, the energy loss per cycle is decreased by the anisotropy compared to the isotropic case when only dynamical effects are taken into account. Thus, in this case, in the low-frequency limit, a better heating efficiency can be achieved for isotropic nanoparticles. The possible role of thermal fluctuations is also discussed. Results obtained are compared to experimental data.
确定性的朗道-栗弗席兹-吉尔伯特方程已被用于研究具有单轴各向异性的磁性纳米颗粒在旋转磁场驱动下的磁化非线性动力学和比功率损耗，推广了P. F. 德沙泰尔、I. 南多里、J. 哈克尔、S. 梅萨罗斯和K. 瓦德 [《凝聚态物理杂志》21, 124202 (2009)] 针对各向同性情况所得到的结果。与单畴铁磁颗粒中许多旨在使损耗最小化的磁化反转应用不同，在本文中，我们研究了通过热疗用于癌症治疗的耗散机制，这需要增强能量损耗。我们表明，对于圆极化场，在仅考虑动力学效应时，与各向同性情况相比，各向异性会使每周期的能量损耗降低。因此，在这种情况下，在低频极限下，各向同性纳米颗粒可实现更好的加热效率。还讨论了热涨落的可能作用。将所得结果与实验数据进行了比较。
