Magneto-volume Effects in Fe-based Amorphous Alloys

铁基非晶合金的磁体积效应

基本信息

批准号：
04402045
负责人：
FUKAMICHI Kazuaki
金额：
$ 13.44万
依托单位：
TOHOKU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (A)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1994
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-04402045/
关键词：
Pressure effect Magnetovolume effect Law of approach to saturation Random axial magnetic anisotoropy Hydrogen absorption Valence Spin glass Structural analysis 磁気弾性効果圧縮率ブリュアン散乱 4極子分裂アイソマーシフト磁気相図 20面体クラスター希土類元素熱膨張

项目摘要

The pressure effects on the Curie temperature and magnetization for Fe-based amorphous alloys which have large magnetovolume effects have been investigated. The magnetization curves for the alloys with a very high concentration of Fe do not follow the law of approach to saturation with 1/H but follow that with 1/H^<1/2>. The latter power law is valid for the alloy systems which have antifferomagnetic interactions. It should be noted that the curves for random axial magnetic anisotropy alloy systems do not follow the 1/H^<1/2> law.The temperature and field dependences of linear and forced volume magnetostrictions have been investigated. These two values are markedly large and the forced-volume magnetosriction exhibits a tendency to diverge at the spin freezing and the Curie temperatures. These results are very different from those for the localized systems.The dramatic increase in the magnetization is caused by hydrogenation for Ce-Fe amorphous alloys. We can expect a huge coercivity at low temperatures due to the random magnetic anisotropy if the valence of Ce is reduce from tetravalent to trivalent by hydrogenation. However no such a large coercivity has been confirmed. This behavior is explained by the aggregation of hydrogen atoms around Ce atoms, resulting in the altered electronic structure. Therefore, we can not assume that the expansion of volume by hydrogenation as the negative pressure.The changes in the magnetic properties by annealing for amorphous Y-Fe alloys are correlated to the increases in the interatomic distance of Fe-Fe pairs and the coordination numbers of Fe atoms.

已经研究了对具有巨大磁化效果的Fe基温度和磁化的压力影响。 Fe浓度很高的合金的磁化曲线不会遵循1/H的饱和方法，但使用1/H^<1/2>遵循。后一种功率定律适用于具有抗不同磁相互作用的合金系统。应当指出的是，随机轴向磁各向异性合金系统的曲线不遵循1/H^<1/2>法律。已研究了线性和强制体积磁盘的温度和场依赖性。这两个值明显很大，并且强制体积磁体训练表现出在自旋冷冻和居里温度下发散的趋势。这些结果与局部系统的结果大不相同。磁化强度的增加是由CE-FE无定形合金的氢化引起的。如果CE的价从四载体降低到通过氢化的三价，我们可以预期由于随机磁各向异性，由于随机磁各向异性，我们可以期望在低温下具有巨大的训练性。但是，尚未确认如此巨大的胁迫。这种行为是通过CE原子周围的氢原子的聚集来解释的，从而导致电子结构改变。因此，我们不能假设通过氢化作为负压扩大体积。通过退火而通过退火而导致的磁性变化与Fe-Fe对的原子间距离的增加以及Fe原子的协调数的增加相关。