Observation of a Main Fermi Surface in UPt_<b>3</b>

Abstract

We have performed the de Haas-van Alphen (dHvA) experiments in UPt 3 . A new branch has been observed in a relatively wide angle region. It has a large cyclotron effective mass of 80 m 0 and the dHvA frequency is 5.66 ×10 7 Oe for the field along the [0001] direction. The new branch most likely corresponds to the main electron Fermi surface in the 37th band of the 5 f -itinerant band model.