Magnetic susceptibility of NaxV2O5−β

The magnetic properties of Nax V2 O5−β vanadium bronzes have been studied on single crystals with x=0.20, 0.30 and 0.33. Curie behaviour has been found for all samples. For x=0.33, a magnetic transition takes place at T1?18 K. The initial reversible susceptibility, thermoremanent and isothermal remanent magnetizations have been measured at T<18 K for different crystallographic orientations. The data suggest an antiferromagnetic behaviour with the direction of antiferromagnetism perpendicular to the b↘-monoclinic axis. The remanent magnetizations are compared to a spin glass behaviour due to a possible position disorder of the V4+. It is also proposed that there could be a weak ferromagnetism along the b↘-axis.