Magnetoresistance and de Haas-van Alphen Effect in CeRu2Si2and LaRu2Si2

Abstract

We have measured the magnetoresistance and de Haas-van Alphen (dHvA) effect in CeRu 2 Si 2 and LaRu 2 Si 2 . From the results of magnetoresistance, CeRu 2 Si 2 is concluded to be a compensated metal, possibly possessing an open orbit along the c -axis of the tetragonal structure. On the other hand, LaRu 2 Si 2 is an uncompensated metal, showing the saturated magnetoresistance. These results imply that the 4 f electrons in CeRu 2 Si 2 are itinerant. In the dHvA experiments of LaRu 2 Si 2 , we have found a large ellipsoidal Fermi surface which occupies roughly half of the Brillouin zone in volume. On the other hand, CeRu 2 Si 2 possesses multiply connected Fermi surfaces in part, although main Fermi surfaces are not observed yet.