A comprehensive transport investigations on the systems exhibiting the giant magnetoresistance

对表现出巨磁阻的系统进行全面的输运研究

基本信息

批准号：
06640486
负责人：
SATO Hideyuki
金额：
$ 1.34万
依托单位：
Tokyo Metropolitan University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

项目摘要

(1)To investigate how the spin-glass transition compete with the interlayr coupling in magnetic multilayrs, we have measured the magnetization, magnetoresistance (MR), Hall effect and thermoelectric power of Cu (Mm) /Co multilayrs. We found a clear evidence of the competition such as an increment of the saturation field. Most prominent feature was found on the sample with Cu (Mn) layr thickness near 15A where we expect a ferromagnetic coupling as in the sample with pure Cu layrs. The coupling was ferromagnetic at room temeprature, however, an antiferromagnetic component grew enormously below 70K.The result can be understood partially as due to the combined effect of the spin-glass transition and the interlayr coupling. (2) We previously reported that the large field dependence of scattering probability of conduction electron appeared in the anomalous Hall resistivity. However, it is not settled yet. In order to make sure the fact, we made simultaneous measurements of the Hall effect and MR on CO (Fe) /Cu multilayrs which exhibits the MR oscillation most clearly. We found a clear oscillation of anomalous Hall coefficient synchronized with the MR oscillation. We also found a synchronized oscillation in the thermoelectric power. (3) We measured the field dependence of the Hall effect, thermoelectric power and thermal conductivity on the two typical granular alloy system Co-Ag and Co-Cu, and found all the properties exhibit the field dependence correlated with the giant MR effect. We inferred that the basic mechanism of the giant MR effect in the granular alloys is same as that in multilayrs. (4) We have investigated the field dependence of various transport properties on UNiGa which shows a large MR effect to be discussed in relation to the magnetic multilayrs. We also found the large magnetic field effect in all the measured properties. From the Hall effect and thermoelectric power, we judged that the Fermi surface changes in the spin reorientation transition.

(1)为了研究磁性多层膜中自旋玻璃化转变如何与层间耦合竞争，我们测量了Cu(Mm)/Co多层膜的磁化强度、磁阻(MR)、霍尔效应和热电势。我们发现了明显的竞争证据，例如饱和场的增加。最突出的特征是在 Cu (Mn) 层厚度接近 15A 的样品上发现的，我们预计会像纯 Cu 层的样品一样出现铁磁耦合。该耦合在室温下是铁磁性的，然而，反铁磁性成分在70K以下急剧增长。结果可以部分理解为由于自旋玻璃转变和层间耦合的综合效应。 (2)我们之前报道了反常霍尔电阻率中出现了传导电子散射概率的大场依赖性。不过，事情还没有解决。为了确定这一事实，我们同时测量了 CO (Fe)/Cu 多层膜上的霍尔效应和 MR，其中 MR 振荡最为清晰。我们发现异常霍尔系数的明显振荡与 MR 振荡同步。我们还发现热电功率存在同步振荡。 (3)测量了Co-Ag和Co-Cu两种典型颗粒合金体系的霍尔效应、热电势和热导率的场依赖性，发现所有性能均表现出与巨磁流变效应相关的场依赖性。我们推断颗粒合金中巨磁流变效应的基本机制与多层合金中的巨磁流变效应的基本机制相同。 (4) 我们研究了 UNiGa 上各种输运特性的场依赖性，这表明与磁性多层相关的大磁流变效应值得讨论。我们还发现所有测量的特性都存在大的磁场效应。从霍尔效应和热电势，我们判断费米面在自旋重定向跃迁中发生变化。