CONICAL SPIRAL IN TB5SB3 COMPOUND

Neutron diffraction measurements performed on the Tb//5Sb//3 compound, which crystallizes in the hexagonal Mn//5Sb//3-type structure, indicate that the magnetic structure of the compound is a conical spiral between 150 and 80 K with a propagation vector k equals left bracket 0, 0, 0. 1414 right bracket and terbium magnetic moments 5. 8 and 3. 5 mu //B for the two sites, respectively. The axis of the cone makes an angle of 51. 5 degree with the c-axis of the crystal at 100 K. The angle between the axis of the cone and the direction of the moments of both sites is found to be 28. 5 degree . Below 80 K the diagram becomes complicated with many peaks at low angles with more than one propagation vector.