Continuous evolution of fermi surface properties above metamagnetic transitions in CexLa1-xRu2Si2

We report the de Haas-van Alphen (dHvA) effect studies above metamagnetic transition fields in CexLa1-xRu2Si2. Three dHvA oscillations beta', gamma', and delta are observed for all the samples from x = 0.0 to 1.0. The frequencies and effective masses of these oscillations vary smoothly with the Cc concentration from LaRu2Si2 to CeRu2Si2. The signal magnitude is reduced only by a factor of approximately 1/10 at most even in alloys with a high concentration of Ce. These behaviors are the same as those observed in the alloys of the compounds with localized f electrons, indicating that the f electron maintains localized nature above the metamagnetic transitions.