HEAVY FERMIONS SURVIVE THE METAMAGNETIC TRANSITION IN UPD2AL3

The electronic structure above the metamagnetic transition (H-m) in UP d2Al3 is investigated by means of the de Haas-van Alphen (dHvA) effect . Two dHvA frequencies, 1270 and 3000 T, are observed for H\\[100]. Th e cyclotron effective masses are found to be 5.4m(0) and 31m(0) respec tively. The heavy mass of the latter branch indicates that the heavy-f ermion state persists above H-m. The angle dependence of both frequenc ies is determined and compared with the dHvA frequency branches below H-m.