Fermi Surface Studies of Heavy Electron System by the de Haas-van Alphen Experiments

通过De Haas-van Alphen(DHvA)实验测定了Ce和U重电子系统的费米表面性质。我们研究过的化合物大约有十二种。重要的dHvA结果总结如下：(1)我们从CeIn3的dHvA实验中澄清了回旋质量与散射寿命的关系。回旋质量越大，散射寿命越大，使得回旋质量和反散射寿命的乘积是恒定的。(2)重电子系统中另一个重要的问题是弱磁性，这与变磁行为有关。测量了LaRu_2Si_2和CeU_2Si_2的磁阻和dHvA效应。结果表明，LaRu_2Si_2的费米面是未补偿的金属，具有占据布里渊区一半的大椭球费米面。另一方面，CeU_2Si_2是补偿金属，因此CeU_2Si_2中的4f电子是巡游的。当磁场沿c轴方向时，在80kOe处发生超磁现象。(3)我们成功地生长了高质量的铁磁性化合物UGe_2单晶。在dHvA实验中探测到了回旋质量为10~(-25)M_0的大回旋载流子。

We have determined the Fermi surface properties of Ce and U heavy electron systems by the de Haas-van Alphen(dHvA)experiments. The number of the compounds which we have studied is about twelve. Important dHvA results are summarized as follows ;(1)We have clarified the relation between the cyclotron mass and the scattering lifetime from the dHvA experiments of CeIn3Namely, the larger the cyclotron mass becomes, the scattering lifetime is, such that the product of the cyclotron mass and the inverse scattering lifetime is constant.(2)Another important problem in the heavy electron system is weak magnetism, which is related to the metamagnetic behavior. we have measured the magnetoresistance and the dHvA effect for LaRu_2Si_2 and CeRu_2Si_2. The Fermi surface of LaRu_2Si_2 is concluded to be an uncompensated metal, possessing a large ellipsoidal Fermi surface which occupies half of the Brillouin zone. on the other hand, CeRu_2Si_2 is a compensated metal, resulting that 4f electrons in CeRu_2Si_2 are itinerant. When the field is directed along the c-axis, metamagnetism occurs at 80 kOe. The 4f character is not clear at higher fields than 80 kOe.(3)We have succeeded in growth a high-quality single crystal of the ferromagnetic compound UGe_2. Carriers with the large cyclotron masses of 10-25m_0 were detected in our dHvA experiments.