A New Approach to Include Surface Contributions in Micromagnetic Simulations of Nanoparticles

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• 作者：N. Ntallis^a ; ^b ; ^{nntallis@physics.auth.gr" class="auth_mail" title="E-mail the corresponding author} ; K.G. Efthimiadis^a ; K.N. Trohidou^b
• 关键词：Micromagnetism ; Surface effects ; Finite Element Method ; Monte Carlo
• 刊名：Physics Procedia
• 出版年：2015
• 出版时间：2015
• 年：2015
• 卷：75
• 期：Complete
• 页码：1112-1121
• 全文大小：508 K

文摘

In this work a micromagnetic model is presented for ferromagnetic nanoparticles where the surface is treated as a single effective layer and not as a separate shell. The model consists of two coupled Partial Differential Equations (PDE), one for the magnetization vector of the bulk volume and the second for the outer nodes. The strength of the coupling depends on the effective width of the layer. Simulations were made by means of the Finite Element Method (FEM). For a comparison FEM for core/shell type and atomistic Monte Carlo simulations were also performed. Our results show that H_s, the field where reversal takes place, varies as ∼1/D, where D is the particle's radius, with the anisotropy strength for any anisotropy direction. Moreover the computational cost of the effective layer model is lower than the core shell one, thus can be easily extended to larger particles where dipolar interactions should also be taken into account.