Angular dependence of the switching field and implications for gyromagnetic remanent magnetization in three-axis alternating-field demagnetization
Angular dependence of the switching field and implications for gyromagnetic remanent magnetization in three-axis alternating-field demagnetization
复制标题
切换场的角度依赖性以及对三轴交变场退磁中旋磁剩磁的影响
DOI：
10.1111/j.1365-246x.2004.02228.x
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发表时间：
2004
影响因子：
2.8
通讯作者：
K. Madsen
中科院分区：
文献类型：
--
作者：
K. Madsen
摘要
反转单畴 (SD) 晶粒磁矩的临界场（即切换场）是场与晶粒易磁化轴之间角度的函数。相干反转（即自旋一致反转）导出的函数关系不同于各种非相干机制和多畴（MD）晶粒中畴壁运动的函数关系。由于切换场的角度依赖性，单轴交变场 (AF) 退磁的效率低于样品翻滚的 AF 退磁。确定了具有非磁滞和旋转剩磁（分别为 ARM 和 RRM）的合成岩石样品和天然岩石样品的差异。选择这些类型的剩磁来主要激活 SD 晶粒，并根据磁性晶粒尺寸讨论它们相对于饱和等温剩磁 (SIRM) 的大小。对于所研究的样本，数据表明大多数剩磁载流子不能与相干反转的斯托纳-沃尔法斯模型相关联。相反，不相干的反转或磁畴壁运动在很大程度上解释了观察到的滞后。基于这些模型对应的开关场的角度依赖性，讨论了三轴退磁期间旋磁剩磁（GRM）的获取。特别是从理论上表明，Dankers和Zijderveld的方法未能完全消除三轴退磁中GRM的影响。
SUMMARY
The critical field for reversing the magnetic moment of a single-domain (SD) grain, the switching field, is a function of the angle between the field and the grain's easy axis of magnetization. The functional relationship derived for coherent reversal, i.e. spins reversing in unison, differs from that of various incoherent mechanisms and of domain wall movement in multidomain (MD) grains. Due to the angular dependence of the switching field, uniaxial alternating-field (AF) demagnetization is less efficient than AF demagnetization with tumbling of the sample. The difference was determined for synthetic and natural rock samples carrying anhysteretic and rotational remanent magnetizations (ARM and RRM respectively). These types of remanence were chosen to activate dominantly SD grains, and their magnitudes relative to saturation isothermal remanent magnetization (SIRM) are discussed in relation to magnetic grain size. For the samples studied, data indicated that the majority of remanence carriers cannot be associated with the Stoner–Wohlfarth model for coherent reversal. In contrast, incoherent reversal or domain wall movement largely explains the observed lag. Based on the angular dependence of switching field corresponding to these models, the acquisition of gyromagnetic remanent magnetization (GRM) during three-axis demagnetization is discussed. In particular it is shown theoretically that the method of Dankers and Zijderveld fails to eliminate completely the effect of GRM in three-axis demagnetization.