ESR and Cyclotron Resonance of Strongly Correlated Materials

强相关材料的 ESR 和回旋共振

基本信息

批准号：
08404022
负责人：
MOTOKAWA Mitsuhiro
金额：
$ 25.47万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A).
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1999
项目状态：
已结题

项目摘要

Continuing the experiments done last year, we have performed the magnetic resonance and cyclotron resonance on some rare-earth compounds using vector network analyzer system developed recently at ultra low temperatures and high magnetic fields. A microwave cavity has been used for high sensitivity. The frequency range is 40〜110 GHz and the temperature range is 0.5〜300 K. The obtained results are as follows :1) GdAs : The magnetic structure of this compound with easy (111) plane, which had been unknown so far, has been determined by ESR. The cyclotron resonance has been observed at 0.5 K and the effective mass of the carrier is detemined as 0.48 m0. This result suggests that the fermi surface is spherical and the effective mass is two times larger than that obtained by quantum oscillation.2) LaSb : The cyclotron resonance has been observed below 4.2 K. From the anisotropic behavior of the resonance position, this resonance occurs due to carriers with a ellipsoidal fermi surface. The effective mass obtained is 0.26 m0 along the <100> direction and is two times larger than that obtained by quantum oscillation.The difference between masses obtained by cyclotron resonance and quantum oscillaation has been observed for low dimensional organic conductors. However the former is larger than the latter and consistent with the theoretical prediction, which is against our result. In this study, we have first observed the cyclotron resonance on strongly correlated materials, which has never reported, and determined the effective mass directly. The theory to explain our result has not been done yet.

继续去年进行的实验，我们使用了最近在超低温度和高磁场上开发的矢量网络分析仪系统对一些稀有地球化合物进行了磁共振和回旋共振。微波腔已用于高灵敏度。频率范围为40-110 GHz，温度范围为0.5-300K。获得的结果如下：1）GDAS：该化合物的磁性结构，带有Easy（111）平面，到目前为止尚不清楚，已由ESR确定。在0.5 K处观察到了回旋子共振，并且载体的有效质量确定为0.48 m0。该结果表明，费米表面是球形的，有效的质量比量子振荡获得的质量大两倍。2）LASB：在4.2 K以下观察到的回旋子共振。从共振位置的各向异性行为中，这种共振是由于携带者而引起的，这是由于携带者带来了椭圆形的Fermi Fermi表面。沿<100>方向获得的有效质量为0.26 m0，比通过量子振荡获得的质量大两倍。对于低维有机导体，已经观察到通过回旋共振和量子振荡获得的质量之间的差异。然而，前者大于后者，并且与理论预测一致，在这项研究中，我们首先观察到对强相关材料的回旋共振，该材料从未报告过，并直接确定了有效质量。解释我们结果的理论尚未完成。