Magnetic structure of the CeScSi-type RScGe compounds (R = Pr, Nd, Tb)

Subsequent magnetic transitions were recently reported for the CeScSi-type RScGe (R = rare earth) equiatomic intermetallic compounds. The compounds TbScGe and NdScGe order ferromagnetically at T_C = 216 K and T_C = 200 K, respectively whereas PrScGe orders antiferromagnetically at T_N = 140 K. In addition, PrScGe demonstrates two other magnetic transitions at T_C1 = 88 K and T_C2 = 80 K in an applied field of 5 kOe. An investigation by neutron diffraction has been now carried out on these phases in an attempt to solve the magnetic structures corresponding to each ordering, and in this article the results obtained are reported. Below the Curie point, the magnetic structure of TbScGe and NdScGe is collinear ferromagnetic. The magnetic moment of Tb atoms coincides with the Z-axis of CeScSi-type unit cell (M_Tb = 8.63μ_B at 2 K), whereas the magnetic moment of Nd atoms has the θ = 52(2)° angle with Z-axis (M_Nd = 3.53(2)μ_B at 2 K). Below the Néel temperature, T_N = 140 K the magnetic structure of PrScGe consists of antiferromagnetic (0 0 2) rare-earth double layers with magnetic moments of the rare earth atoms collinearly ordered. The magnetic moments of Pr atoms (M_Pr = 1.72(3)μ_B at 100 K) have the θ = 62(2)° angle with the Z-axis. Between T_C1 = 82 K and T_C2 = 62 K the conversion of the commensurate antiferromagnetic collinear type structure to the ferrimagnetic collinear type structure with propagation vector K = 0, 0, 1/2] was observed: the magnetic moments of Pr double layers became sine modulated along the Z-axis. Below T_C2 = 62 K the magnetic structure of PrScGe compound consists of ferrimagnetic (0 0 1/2) layers (amplitude of Pr magnetic moment M_Pr = 3.31(9)μ_B at 5 K).