Angle-resolved Magnetization Measurements on Antiferroquadrupolar Ordering System PrPb3: Evidence for Anisotropic Quadrupolar Interaction

Angle-resolved magnetization measurements have been performed on PrPb 3 at temperatures down to 0.35 K and magnetic fields up to 4 T to examine the field-orientational dependence of the antiferroquadrupolar (AFQ) ordering temperature T Q in detail. Field rotation within the (001) and (110) planes revealed that T Q takes a v-shape minimum not only along the [111] direction but also along the [110] direction. The results are incompatible with those obtained using an isotropic AFQ interaction model, and strongly suggest the existence of an anisotropic AFQ interaction that stabilizes the O 2 0 phase or its equivalents in all directions in a wide field range.