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Study of Itinerant Electron Magnetism on Amorphous (Hf, Ta)Fe_2 Alloys

非晶(Hf,Ta)Fe_2合金的巡回电子磁场研究

基本信息

批准号：
04640319
负责人：
MURAYAMA Shigeyuki
金额：
$ 1.22万
依托单位：
Muroran Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1993
项目状态：
已结题

项目摘要

Hexagonal Laves-phase pseudo-binary intermetallic (Hf, Ta)Fe_2 alloys show two-stage magnetic transition : para- antiferro- ferro-magnetism with decreasing temperature. We have made a detailed study of the magnetism on amorphous (Hf, Ta)Fe_2 alloys obtained from high-rate dc sputtering technique.1. The magnetization and Mossbauer effect have been measured. The ferromagnetic moment and Curie temperature of the amorphous alloys continuously decrease with increasing Ta concentration x and well follow the Rhodes-Wohlfarth curve. This is a typical character of the itinerant electron ferromagnetism. The local Fe moment is found to be inhomogeneously distributed depending on the local environment effects.2. The thermal expansion has been measured by using gauge method. A positive magnetovolume effect has been observed near and below the Curie temperature. This magnitude decreases with increasing x and almost disappears for x >= 0.7.3. The specific heat has been measured by using light-chopped ac method. A small peak in the specific heat has been measured at about the Curie temperature for x =< 0.3. Below 10 K the temperature dependence of the specific heat follows gammaT + betaT^3. The coefficient of the electronic specific heat gamma is much larger compared for the common metal and even larger than the crystalline phase with the same chemical composition.4. The resistivity and magnetoresistivity have been measured. The amount increased below the Curie temperature in the resistivity agrees with the universal function of the ferromagnetic moment with the Ta concentration and external field with implicit parameters. These facts suggest that the variation of the resistivity is mainly due to the magnetic scattering of the conduction electron at the local Fe site. Below 10 K it follows T^<1/2> law and is almost independent of x. This seems to be due the contribution from the fundamental amorphous structure and will be a next interesting subject.

六方lave相伪二元金属间化合物（Hf, Ta）Fe_2合金表现出两阶段的磁性转变：随温度的降低，从准反铁磁性到铁磁性。本文对高速直流溅射法制备的非晶（Hf, Ta）Fe_2合金的磁性进行了详细的研究。测量了磁化强度和穆斯堡尔效应。随着Ta浓度x的增加，非晶合金的铁磁矩和居里温度不断降低，并符合Rhodes-Wohlfarth曲线。这是流动电子铁磁性的一个典型特征。发现局部铁矩随局部环境的影响呈非均匀分布。用量规法测量了热膨胀。在居里温度附近和以下观察到正磁体积效应。该量级随着x的增加而减小，当x >= 0.7.3时几乎消失。用切光交流法测量了比热。在居里温度附近，当x =< 0.3时，比热有一个小的峰值。在10k以下，比热对温度的依赖关系为gamma + betaT^3。与普通金属相比，电子比热系数要大得多，甚至比具有相同化学成分的结晶相还要大。测量了电阻率和磁电阻率。电阻率在居里温度以下增加的量符合铁磁矩与Ta浓度的通用函数和带隐式参数的外场。这些事实表明，电阻率的变化主要是由于导电电子在局部铁位点的磁散射。在10 K以下，它遵循T^<1/2>定律，几乎与x无关。这似乎是由于基本非晶结构的贡献，将是下一个有趣的主题。