Ferromagnetic Resonance Porosity Linewidth Theory in Polycrystalline Insulators
Ferromagnetic Resonance Porosity Linewidth Theory in Polycrystalline Insulators
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DOI：
10.1063/1.1703089
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发表时间：
1965-05
影响因子：
3.2
通讯作者：
M. Sparks
中科院分区：
文献类型：
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作者：
M. Sparks
多晶样品中铁磁共振线宽的两个来源在单晶样品中不存在：（1）由于各向异性能量轴从微晶到微晶的随机取向而导致各个微晶的谐振频率的变化，以及（2）微晶之间的孔隙产生的退磁场。发展了一种理论，该理论用孔隙退磁场引起的双磁振子散射来解释对线宽的第二个贡献。理论结果与实验结果吻合较好。本理论考虑了偶极子线宽的变窄，而Schlomann之前的独立晶粒理论则没有考虑。 Geschwind 和 Clogston 的第二个先前理论做出了必要的数学近似，而当前的理论是基于物理模型。
Two sources of ferromagnetic resonance linewidth in polycrystalline samples which are absent in single‐crystal samples are: (1) the variation in resonant frequencies of the individual crystallites due to the random orientation of the anisotropy energy axes from crystallite to crystallite, and (2) the demagnetization fields arising from the pores between the crystallites. A theory is developed which explains this second contribution to the linewidth in terms of the two‐magnon scattering induced by the demagnetization fields of the pores. Agreement of the theoretical results with experiments is good.The present theory takes into account the dipole narrowing of the linewidth, whereas the previous independent grain theory of Schlomann does not. A second previous theory by Geschwind and Clogston makes an essential mathematical approximation, while the present theory is based on a physical model.