de Haas-van Alphen effect in thallium

The de Haas-van Alphen (dHvA) effect in single crystals of high-purity thallium has been investigated in magnetic fields up to 55 kOe. These measurements extend previous work by providing accurate dHvA frequencies for field directions in the three principal crystallographic planes. dHvA frequencies larger than 10(7) G are assigned to orbits on the third-zone hole surface centered at A and the fourth-zone hexagonal network of Soven's relativistic orthogonalized-plane-wave model. Comparisons with the single-orthogonalized-plane-wave Fermi-surface model are also made. Magnetic breakdown of some of the orbits is observed. Lower dHvA frequencies are assigned to a small dumbbell-shaped surface with symmetry (6) over bar m2. The cyclotron masses of orbits on this surface are also presented and compared with recent cyclotron resonance results.