Abstract

A method has been proposed for calculating linear dynamic magnetization of a viscoelastic ferrocolloid in a constant magnetic field (displacement field). The magnetic phase of the colloid consists of Brownian ferromagnetic nanoparticles placed into a Jeffry’s fluid. Therefore, each particle, upon its rotation induced by an alternating (probe) field, dissipates energy via two friction “channels” operating in parallel. The usual (Newtonian) viscosity prevails at short times, while the retarded (Maxwellian) dissipative interaction plays the main role at long times. It has been shown that the retarded friction on the Jeffry’s medium gives rise to a slow magnetization relaxation mode, which must be most pronounced in ferrocolloids having substantial elasticity. As the displacement field is enhanced, this mode weakens and the friction relevant to the Newtonian viscosity becomes prevailing, because it causes small-angle orientational fluctuations of particle magnetic moments. The proposed method yields an exact solution of the model, and the results obtained using method prove that previous approximate calculations are substantially limited.

中文翻译：

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粘弹性铁胶体中的磁弛豫

摘要

已经提出了一种用于在恒定磁场（位移场）中计算粘弹性铁胶体的线性动态磁化的方法。胶体的磁性相由置于杰弗里流体中的布朗铁磁性纳米颗粒组成。因此，每个粒子在交变（探测）场感应下旋转时，会通过两个平行运行的摩擦“通道”耗散能量。通常的（牛顿）粘度在短时间内占主导地位，而延迟的（麦克斯韦）耗散相互作用则在长时间内起主要作用。已经表明，在杰弗里介质上的延迟摩擦引起缓慢的磁化弛豫模式，这在具有显着弹性的铁胶体中必须最明显。随着位移场的增加，这种模式减弱，与牛顿粘度有关的摩擦变得普遍，因为它会引起粒子磁矩的小角度取向波动。所提出的方法产生了模型的精确解，并且使用该方法获得的结果证明了先前的近似计算受到了很大的限制。