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

Abstract

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 = 8.63 μ 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).