Nanoscale Brownian heating by interacting magnetic dipolar particles
Nanoscale Brownian heating by interacting magnetic dipolar particles
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DOI：
10.1038/s41598-017-01760-x
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发表时间：
2017-05-10
影响因子：
4.6
通讯作者：
Devaud, Martin
中科院分区：
文献类型：
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作者：
Chalopin, Yann;Bacri, Jean-Claude;Devaud, Martin
磁性纳米粒子簇在各个研究领域都受到了极大的关注。它们在交变磁场下产生热量的能力最近为诸如通过热疗治疗癌症等应用开辟了道路。本工作试图研究嵌入磁性纳米颗粒（MNP）中的相互作用偶极子的集体效应，以预测它们与液体的热耗散。首先，我们提出了一个通用的方法，基于微观偶极波动的跟踪，访问任何空间分布的MNP的耗散谱。没有任何其他假设的线性响应制度，它表明，增加颗粒浓度（偶极相互作用）显着减少和蓝移的耗散过程。这种效应起源于一个优势的耦合能量超过布朗扭矩，这创造了一个长程有序饱和的系统对外部字段的响应。因此，粒子密度对于控制电磁能量的吸收及其随后以热的形式耗散是至关重要的。
Clusters of magnetic nanoparticles have received considerable interest in various research fields. Their capacity to generate heat under an alternating magnetic field has recently opened the way to applications such as cancer therapy by hyperthermia. This work is an attempt to investigate the collective effects of interacting dipoles embedded in magnetic nano-particles (MNP) to predict their thermal dissipation with a liquid. We first present a general approach, based on the tracking of the microscopic dipole fluctuations, to access to the dissipation spectra of any spatial distribution of MNPs. Without any other assumption that the linear response regime, it is shown that increasing the particle concentration (dipolar interactions) dramatically diminishes and blueshifts the dissipation processes. This effect originates in a predominance of the coupling energy over the Brownian torques, which create a long-range ordering that saturates the response of the system to an external field. Consequently, the particle density is of fundamental importance to the control of the absorption of electromagnetic energy and its subsequent dissipation in the form of heat.