De Haas-van Alphen effect in ytterbium and uranium compounds

We have measured the de Haas-van Alphen (dHvA) effects of YbSn3, ZbZn(11) and UGa2 in the He-4 temperature range up to 15 T. The results for YbSn3 show that the dHvA frequencies range from 60 to 3000 T and the cyclotron masses from 0.13m(0) to 0.44m(0), where m(0) is the free electron mass. For YbZn11 the dHvA frequencies range from 200 to 11 000 T and the cyclotron masses are nearly the same as those of YbSn3. These results indicate that YbSn3 is a compensated metal and Yb ions in YbSn3 and YbZn11 are divalent. The dHvA frequencies of UGa2 range from 20 to 1300 T. The observed cyclotron masses range from 0.3m(0) to 3.3m(0), which are larger than those of YbSn3 and YbZn11 by a factor of ten. Field dependence of the dHvA frequency is observed in the lowest frequency oscillations in UGa2. These results indicate that the 5f electrons in UGa2 hybridize appreciably with the conduction electrons. (C) 1998 Elsevier Science S.A.