High field De Haas-van Alphen studies in the charge density wave state of the quasi two-dimensional monophosphate tungsten bronze P4W12O44

De Haas-van Alphen studies have been performed on the quasi two-dimensional monophosphate tungsten bronze P4W12O44 with a capacitive torquemeter in magnetic fields up to 28 Teslas and at temperatures down to 0.3K. Several frequencies due to the small carrier pockets left by the charge density wave gap openings are found. Effective masses of the order of 0.3 the free electron mass have been obtained from the temperature dependence of the oscillations amplitude. Angular dependence of the frequencies and of the cyclotron masses is consistent with quasi-cylindrical Fermi surface pockets.