The de Haas-van Alphen effect is used to study angular dependent extremal
areas of the Fermi Surfaces (FS) and effective masses of CexLa1−xB6 alloys for x between 0 and 0.05. The FS of these alloys was previously
observed to be spin polarized at low Ce concentration (x = 0.05). This work
gives the details of the initial development of the topology and spin
polarization of the FS from that of unpolarized metallic LaB6 to that of
spin polarized heavy Fermion CeB6 .Comment: 7 pages, 9 figures, submitted to PR