Metamagnetic transition in UPt3 studied by high-field magnetization and deHaas-van Alphen experiments

A heavy fermion superconductor UPt3 exhibits the metamagnetic transition at about 20 T. High-held magnetization experiments reveal that this transitio n persists up to about 30 K, which is close to the characteristic temperatu re T-chi max (similar or equal to 20 K) where the magnetic susceptibility h as a maximum in the temperature dependence. Below T-chi max, the magnitude of magnetic fluctuations increases and forms the heavy fermion state at low temperatures. This is reflected in the growth of the cyclotron effective m ass. The mass in the main band 37-electron Fermi surface, which was determi ned by the de Haas-van Alphen experiments, is strongly enhanced with increa sing the held, from 63m(0) at 12.5 T to 86m(0) at Is T. This is consistent with the field dependence of the electronic specific heat coefficient. [S01 63-1829(99)04534-8].