De Haas-van Alphen Effect in Rare-earth Gallium Compounds RGa2

利用该资助项目购置的10块超导磁体搭建了德哈斯-范阿尔芬效应测量系统。利用该测量系统，在5 T ~ 10 T的磁场范围内，测量了反铁磁SmGa_2和PrGa_2及其参考物质LaGa_2在4 He温度范围内的dHvA效应。(1)反铁磁SmGa 2和PrGa 2的费米面与LaGa 2的费米面非常相似，尽管这些化合物的4-f态不同。(2)在PrGa 2和SmGa 2中观察到的变磁相变导致电子自旋和4-f轨道自旋之间的场诱导交换相互作用。(3)费米面的嵌套效应稳定了PrGa 2中观察到的调制磁结构。(4)反铁磁态的费米面不同于顺磁态的费米面。(5)SmGa_2中存在由于s-f混合效应引起的电子质量增强。我们将继续研究重稀土原子和Ga化合物的dHvA效应。

The measuring system of de Haas-van Alphen effect using the 10 superconducting magnet purchased with this grant-in aid was constructed. We have measured the dHvA effect of antiferromagnetic SmGa2 and PrGa2, and their reference substance LaGa2 in the 4He temperature range with use of this measuring system in the field ranging from 5T to 10 T.We have obtained the following results from the measurement. (1) The Fermi surfaces of antiferromagnetic SmGa2 and PrGa2 are very similar to that of LaGa2 in spite of differences in 4-f states in these compounds. (2) Metamagnetic phase transition observed in PrGa2 and SmGa2 results in the field induced exchange interaction between electron spin and 4-f orbital spin. (3) The nesting effect of the Fermi surface stabilizse the modulated magnetic structure observed in PrGa2. (4) The Fermi surfaces for antiferromagnetic state differ from that of paramganetic state in SmGa2. (5) The electron mass enhancement due to s-f mixing effect is suggested to occur in SmGa2.We will continue to invesigate the dHvA effect on compounds of heavy rear-earth atoms and Ga.