de Haas-van Alphen effect and the band structure of URh3

We have performed measurements of the de Haas-van Alphen (dHvA) effect in the intermetallic compound U${\mathrm{Rh}}_3$, a material with a partially filled $5f$ shell. Complex dHvA spectra containing several frequencies were observed and Fourier analyzed with an on-line computer. Effective-mass measurements were made for several orbits and values as large as 5.3 were observed. Much of the data are consistent with amultiply connected surface whose shape is discussed. In addition to the dHvA experiments, a detailed band-structure calculation was performed using the nonflat relativistic-augmented-plane-wave formalism. The Fermi surface deduced from these calculations is in qualitative agreement with the experimental observation.