Spin-split fermi surfaces in CexLa1-xB6CexLa1-xB6 and PrxLa1-xB6PrxLa1-xB6

We have performed the dHvA measurements on CexLa1-xB6CexLa1-xB6 and PrxLa1-xB6PrxLa1-xB6 compounds to study spin splitting of the Fermi surfaces. In PrB66 we have found new frequency branches to confirm that the Fermi surface splits into up and down spin Fermi surfaces, whereas no spin splitting has been found for x=0.25,0.5,0.75x=0.25,0.5,0.75. We have also found several new frequency branches in CeB6CeB6. The new frequency branches imply that the Fermi surfaces of up and down spin conduction electrons are significantly different in CeB6CeB6 as well as in PrB6PrB6.