单畴磁纳米颗粒磁矩快速翻转特性的研究

摘要

本文利用微磁学方法对立方体单畴磁纳米颗粒的磁矩翻转特性进行了模拟.研究了在只加翻转场时,单畴磁纳米颗粒的阻尼系数、外场对磁矩翻转的影响.结果表明不同参量情况下磁矩翻转所需时间不同,翻转时间长短,随着阻尼系数变化呈反比,随着外场变化呈反比.而对于最小翻转场来说,粒子尺度越小对其要求越大,阻尼系数越大对其要求越小.当固定阻尼系数时,如果外场远大干最小翻转场,不同体积大小的粒子翻转时间趋于一致,这说明外场很大时,粒子尺度影响可忽略.我们还研究了只加偏压场,但外场施加在不同方向时,单畴磁纳米颗粒的阻尼系数对磁矩翻转的影响.%A micro-magnetic simulation was performed for the cubic single domain magnetic nano-particles. The effects of the particle's damping constant, external field on the magnetization reversal were studied when only imposed reversal field was considered.The results show that the time required for magnetic reversal is related to different parame-ters. The reversal time becomes shorter and shorter with the increasing of the damping constant or the external field. The smaller the particle size is, the greater the minimal reversal field and damping constant are required. For a fixed damping constant, when the external field is much larger than the minimal reversal field, the reversal time is independent on the particle size. We al-so studied the effects of the particle's damping constant on the magnetization reversal for the case only biased field was imposed on different directions.