Fermi surface studies of the charge-density-wave state of the quasi-two-dimensional monophosphate tungsten bronzeP4W12O44

The monophosphate tungsten bronze ${\mathrm{P}}_{4}{\mathrm{W}}_{12}{\mathrm{O}}_{44}$ is a quasi-two-dimensional conductor which shows successive Peierls instabilities towards incommensurate charge density wave states. Previous Shubnikov\char21{}de Haas and de Haas\char21{}van Alphen studies performed in the lowest temperature charge density wave state had established that the Fermi surface includes several small quasi cylindrical pockets. We now report angle dependent magnetoresistance oscillations which provide the shape and orientation of one warped Fermi surface pocket. We suggest a possible location of this pocket on the basis of the Fermi surface calculated for the high temperature phase and of the charge density wave nesting vectors.