Delocalization of thefelectron in CexLa1−xRu2Si2- the de Haas-van Alphen effect measurement

We report the first observation of the continuous Fermi surface (FS) variation from La compound (LaRu2Si2) with no f electron to Ce compound (CeRu2Si2) with itinerant f electron via the de Haas-van Alphen (dHvA) effect. The dHvA frequency smoothly varies with Ce concentration and there is no discontinuous change with Ce concentration. It is found that the effective mass and signal amplitude with Ce concentration depends strongly on the Fermi surface sheet, and the effective mass is enhanced toward xc (= 0.91) and the signal amplitude reduces around xc or somewhere between xc and x ∼ 0.8.