The low-field de Haas-van Alphen effect in thallium

A careful study, mainly by the torque method, of the low-field de Haas-van Alphen effect in thallium enables the new long period data to be interpreted in terms of an additional small dumb-bell-shaped Fermi surface with symmetry 6m2 at H in the fifth zone. This is at variance with the ROPW calculation of the band structure but preliminary pseudopotential calculations which were made using the Heine-Abarenkov model potential appear to remove the discrepancy. Additional very long periods of approximately 2*10-5G-1 were observed and are assigned to small hole pockets at M in the third zone or to electrons on the Gamma M line in the fourth zone.