Abstract
A powder sample of the compound Nd was studied by neutron diffraction. The compound is found to be isostructural to the analogous actinide compounds , with as a probable space group and () as ionic positions. The bimolecular unit cell consistent with the room temperature (RT) pattern has the dimensions Å, and Å. A least-squares analysis of 20 lines in the RT pattern yielded a weighted factor of about 9% for two different distributions of the ions: (a) (Nd; Fe; Si); (b) [] with %. The refined parameter is 0.372 for the two distributions. Five superlattice lines were observed in the 4.2 °K pattern. These lines are consistent with a doubling of the unit cell in the direction. These lines are inconsistent with any collinear magnetic structure of tetragonal symmetry of the Fe () sublattice but are consistent with an antiferromagnetic structure of the sublattice. The structure consists of ferromagnetic sheets perpendicular to with the magnetic axis along . These sheets are stacked according to the sequence ++--. This structure belongs to the magnetic space group . The magnetic moment consistent with the diffracted intensities is per Nd ion. The Néel temperature, °K, was determined from the intensity-temperature curve of the strongest superlattice line. This line exhibits a smooth temperature dependence but falls considerably above the Brillouin curve.
- Received 13 July 1972
DOI:https://doi.org/10.1103/PhysRevB.7.3261
©1973 American Physical Society