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

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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.