Theoretical Investigation of Hysteresis and Thermoremanent Magnetization in Multidomain Particles

Newell EAR-0087687多磁区粒子的磁性行为受磁区壁成核和消失以及磁区壁钉扎的控制。人们对这些过程进行了深入的研究，但从未将它们结合在一个单一的自洽模型中。这一建议的目的是发展一个数值微磁模型，该模型包括由于缺陷引起的应力场与磁弹性相互作用。该模型将是无约束的，因此域壁可以自发地成核或消失，并被应力场钉扎。结果将与应力磁铁矿、磁黄铁矿和赤铁矿的区域观测结果进行比较。对于每个被建模的粒子，将使用一种系统的方法来绘制作为外加磁场和温度的函数的所有主要和次要磁化曲线。这些曲线将被用来模拟各种等温和温度相关的实验。

Newell EAR-0087687 The magnetic behavior of multidomain particles is governed by nucleation and disappearance of domain walls and by domain wall pinning. These processes have been studied intensively but never combined in a single self-consistent model. The object of this proposal is to develop a numerical micromagnetic model that includes magnetoelastic interactions with stress fields due to defects. The model will be unconstrained so that domain walls can nucleate or disappear spontaneously and be pinned by the stress fields. Results will be compared with domain observations of stressed magnetite, pyrrhotite and hematite. For each particle that is modeled, a systematic approach will be used to map out all major and minor magnetization curves as a function of applied field and temperature. These curves will be used to simulate a wide variety of isothermal and temperature dependent experiments.