A comprehensive transport investigations on the systems exhibiting the giant magnetoresistance

(1)为了研究多层磁性材料中自旋玻璃转变与层间耦合的竞争关系，我们测量了Cu (Mm) /Co多层材料的磁化强度、磁电阻（MR）、霍尔效应和热电功率。我们发现了一个明显的竞争证据，如饱和场的增加。在Cu （Mn）层厚度接近15A的样品上发现了最显著的特征，我们预计在纯Cu层样品中存在铁磁耦合。这种耦合在室温下是铁磁性的，但在70K以下，反铁磁性成分急剧增加。这一结果可以部分地理解为自旋玻璃跃迁和层间耦合的共同作用。(2)前人报道了异常霍尔电阻率中导电电子散射概率的大场依赖性。然而，这个问题还没有解决。为了证实这一事实，我们同时测量了CO (Fe) /Cu多层材料的霍尔效应和MR振荡，其中MR振荡最明显。我们发现异常霍尔系数的振荡与磁流变同步。我们还发现了热电功率的同步振荡。(3)测量了Co-Ag和Co-Cu两种典型颗粒合金体系的霍尔效应、热电功率和导热系数的场依赖关系，发现所有性能都表现出与巨MR效应相关的场依赖关系。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相同。(4)我们研究了各种输运性质对UNiGa的场依赖性，结果表明，与磁性多层膜有关的大MR效应有待讨论。我们还发现在所有测量的性质中都存在较大的磁场效应。从霍尔效应和热电功率判断，费米表面在自旋重定向跃迁过程中发生了变化。

(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.