Effect of a dc bias field on the dynamic hysteresis of single-domain ferromagnetic particles
Effect of a dc bias field on the dynamic hysteresis of single-domain ferromagnetic particles
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DOI：
10.1063/1.3359722
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发表时间：
2010-04-01
影响因子：
3.2
通讯作者：
Titov, S. V.
中科院分区：
文献类型：
--
作者：
Dejardin, P. M.;Kalmykov, Yu. P.;Titov, S. V.
利用Brown的相干旋转磁化模型，研究了任意幅值交直流叠加磁场下单轴超顺磁性纳米粒子的动态磁滞现象。分析了动态磁滞回线的面积与温度、频率、交直流偏置场的关系。特别是，单畴铁磁粒子的动态磁滞回线在施加相对较弱的直流磁场时发生了很大的改变。此外，研究表明，在中低交流磁场振幅下，直流偏置场允许粒子的磁功率吸收调谐，而在强交流磁场振幅下，这种效果完全类似于交换偏置各向异性所产生的效果。在线性响应区给出了稳态磁化强度和环路面积的简单解析公式，与Brown的Fokker-Planck方程的数值解完全吻合。并与以往的结果进行了比较。(C) 2010年美国物理研究所。(doi: 10.1063/1.3359722)
Dynamic magnetic hysteresis in uniaxial superparamagnetic nanoparticles in superimposed ac and dc magnetic fields of arbitrary amplitude is considered using Brown's model of coherent rotation of the magnetization. The dependence of the area of the dynamic hysteresis loop on the temperature, frequency, and ac and dc bias fields is analyzed. In particular, the dynamic hysteresis loop of a single-domain ferromagnetic particle is substantially altered by applying a relatively weak dc field. Furthermore, it is shown that at intermediate to low ac field amplitudes, the dc bias field permits tuning of the magnetic power absorption of the particles, while for strong ac field amplitudes the effect becomes entirely analogous to that produced by the exchange biased anisotropy. Simple analytical formulas are provided in the linear response regime for the steady-state magnetization and loop area, exhibiting perfect agreement with the numerical solution of Brown's Fokker-Planck equation. Comparison with previous results is also given. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3359722]