磁性皮肤效应在Pb(Fe _{1/2}$Nb _{1/2}$) O3中
N Giles-Donovan1, A D Hillier2, K Ishida2,3
1Centre for Medical and Industrial Ultrasonics, James Watt School of Engineering, University of Glasgow, Glasgow G12 8QQ, United Kingdom.
概括
这项研究揭示了多铁Pb (Fe_{1/2}Nb_{1/2}) O (PFN) 晶体中的磁性"皮肤效应". 子光谱显示磁放松率随深度而变化,与化学成分不同,反映结构放松特性.
科学领域:
- 材料科学 材料科学 材料科学
- 凝聚物质物理学 凝聚物质物理学
- 固态化学 固态化学
背景情况:
- 放松铁电表现出独特的介电性质由于随机的二极电场从化学不均.
- 在放松剂中观察到一个宏观的"皮肤效应",其中接近表面的特性与大部分物质有显著差异.
- Pb(Fe_{1/2}Nb_{1/2}) O3 (PFN) 是一种具有放松器类介电行为和集群旋玻璃磁性质的多铁材料.
研究的目的:
- 通过子光谱学研究PFN单晶中的深度依赖磁放松动态.
- 为了确定化学度的变化是否有助于观察到的磁放松.
- 探索磁性"皮肤效应"的存在和性质,类似于放松器中的结构性皮肤效应.
主要方法:
- 变动动量子光谱 (积极的子旋转放松) 以探测不同深度的磁放松.
- 负元素分析以评估Fe3+和Nb5+的度作为深度的函数.
- 使用伸展指数模型分析子自旋放松数据,以表征放松速率分布.
主要成果:
- 在PFN中,零场正子子旋转放松是由伸展的指数式描述的,表明Fe3+旋转放松率的分布.
- 放松频率的带宽随着子的动量而变化,证实了Fe3+放松动态的深度依赖变化.
- 负元素分析显示Fe3+/Nb5+度与深度的变化很小,排除了化学不均质作为主要原因.
结论:
- PFN表现出磁性"皮肤效应",其中磁性放松动态取决于深度.
- 这种磁性皮肤效应不能归因于化学成分的变化.
- 这些发现表明,放松剂中的结构性皮肤效应与PFN中观察到的磁性行为之间存在类似性.
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