Magnetic ordering in Th3P4-type Tb4Sb3 compound

The nature of the magnetic ordering of Tb4Sb3 compound (Th3P4-type, cubic; cI28, space group I4¯3d, No. 220, a = 0.91518(7) nm) has been investigated by using the techniques of magnetization and neutron diffraction. AC and DC magnetisation measurements indicate antiferromagnetic ordering at ∼108 K in zero magnetic field that is accompanied by a field-induced metamagnetic transition to a ferromagnetic state, in fields above ∼0.3 T. Neutron diffraction experiment in zero applied magnetic field shows that below TN = 112(4) K Tb4Sb3 exhibits an antiferromagnetic flat spiral-type ordering with propagation vector K1 = [±1/8, ±1/8, ±1/8]. The magnetic moment of Tb atoms is found to be MTb = 6.7(3) μB at 80 K. The magnetic moment of Tb atoms lie in the (1 1 1) plane of Tb4Sb3 unit cell (the cone axis arranges along [1 1 1] direction with cone angle β = 90°). Below TN2 ∼ 50 K, Tb4Sb3 shows second antiferromagnetic transition with K2 = [1/2, 1/2, 1/2] with possible re-orientation of Tb magnetic moments.