Interpretation of the Magnetic Order, Neutron Diffraction and 111Cd PAC Studies of NdScGe

Abstract

NdScGe is a ferromagnet with TC = 194(2) K. The magnetic moments of the Nd substructure order along the tetragonal c-axis just below TC and undergo a gradual canting away from the c-axis upon cooling, commencing at around 165 K. We used neutron powder diffraction to show that the Nd magnetic moments lie 70(3)o off the c-axis at 4 K [1]. The apparent discrepancy between our neutron diffraction results and those obtained using PAC [2] (a canting angle of around 32o just below TC , increasing to 45o at 25 K) can be reconciled by placing the principal axis of the electric field gradient tensor in the tetragonal basal plane, rather than along the c-axis, as assumed in the PAC analysis. The unusual temperature dependence of the 111Cd PAC quadrupole frequency at the Sc site, which was interpreted in terms of a lattice softening occurring near the Curie temperature, is shown to be a consequence of the fact that one cannot determine the sign of the quadrupole frequency from a PAC experiment. Finally, we show that the Nd magnetic moments in the canted regime have a [110] basal component rather than [100].