The monophosphate tungsten bronzes (PO2)4(WO3)2m are quasi-two-dimensional conductors which show charge density wave type electronic instabilities. We report electrical resistivity and magnetoresistance measurements down to 0.30 K and in magnetic fields up to 16 T for the m = 7, 8 and 9 members of this family. We show that these compounds exhibit at low temperature an upturn of resistivity and field dependences of the magnetoresistance characteristic of localization effects. We discuss the dimensionality of the regime of localization as m is varied. We show that for m = 7, the regime is quasi-two-dimensional and three-dimensional for m = 8, 9.
- 71.45.Lr Charge-density-wave systems -
- 72.15.Gd Galvanomagnetic and other magnetotransport effects