Fermi surface ofUPt3from 3 to 30 T: Field-induced quasiparticle band polarization and the metamagnetic transition

Abstract

The magnetic-field dependence of the Fermi surface of ${\mathrm{UPt}}_3$ has been studied up to 30 T from 17 to 150 mK using the quantum oscillatory magnetoresistance. Near the 20-T metamagnetic transition, rapid changes in the frequency spectrum indicate strong nonlinear magnetic splitting of the quasiparticle bands; weaker nonlinear splitting is seen at all fields. Above the transition the mass enhancement remains very large, and masses exceeding 100${\mathit{m}}_{\mathit{e}}$ have been observed. Below the transition a surface with mass 170${\mathit{m}}_{\mathit{e}}$ has been found.