论文标题
对磁性纳米颗粒的磁静电作用的多尺度建模，并应用于高温
Multiscale modelling of magnetostatic effects on magnetic nanoparticles with application to hyperthermia
论文作者
论文摘要
我们扩展了基于重新归一化的基于小组的课程元素方法，以进行微磁模拟，以包括适当缩放的磁相互作用。我们将该方法应用于临床相关的动态磁滞回路的模拟中，在磁性高温临床前研究中使用的那种氧化铁纳米颗粒（NP）310 K。粗粒方法，以及涉及扫描速率和吉尔伯特阻尼参数的时间缩放，使我们可以在直径约50 nm的情况下跨长度尺度，并具有合理的模拟时间。对于NP和构成它们的纳米棒，我们报告了有效的单轴各向异性强度和饱和磁化，这与制造的大块材料磁铁矿和Maghemite不同，这是由于温度的非平底效应，体温交换，磁层交换，磁层交换，磁层和nanorod inanorod inanorod of nananorod of of demanter的磁铁矿和磁性磁化。有效参数允许将NP视为单个宏spins，我们发现使用偶极子近似的两个对齐NP计算循环的测试案例，对于超过NP直径的1.5倍的距离就足够了。我们还提出了一项有关将整合时间步长与微磁细胞大小相关联的研究，发现最佳时间步长与细胞体积近似线性尺寸。
We extend a renormalization group-based course-graining method for micromagnetic simulations to include properly scaled magnetostatic interactions. We apply the method in simulations of dynamic hysteresis loops at clinically relevant sweep rates and at 310 K of iron oxide nanoparticles (NPs) of the kind that have been used in preclinical studies of magnetic hyperthermia. The coarse-graining method, along with a time scaling involving sweep rate and Gilbert damping parameter, allow us to span length scales from the unit cell to NPs approximately 50 nm in diameter with reasonable simulation times. For both NPs and the nanorods composing them, we report effective uniaxial anisotropy strengths and saturation magnetizations, which differ from those of the bulk materials magnetite and maghemite of which they are made, on account of the combined non-trivial effects of temperature, inter-rod exchange, magnetostatic interactions and the degree of orientational order within the nanorod composites. The effective parameters allow treating the NPs as single macrospins, and we find for the test case of calculating loops for two aligned NPs that using the dipole approximation is sufficient for distances beyond 1.5 times the NP diameter. We also present a study on relating integration time step to micromagnetic cell size, finding that the optimal time step size scales approximately linearly with cell volume.
