Low-Temperature Magnetic Properties of Some Hexagonal Rare-Earth Trihalides

Abstract

We have made measurements of the low-temperature heat capacity, magnetic susceptibility, and chlorine nuclear quadrupole resonance (NQR) of CeCU, PrCU, NdCl 3 , SmCl 3 , and CeBr 3 . Some measurements have been made on PrBr 3 and NdBr 3 . The experimental results can be closely correlated with antiferromagnetic linear chain models. The NQR shows that long-range order occurs in PrCl 3 at 0.428 K. In NdCl 3 , the NQR line disappeared at 0.50 K and the resonances produced by an internal field appeared at 0.17 K. In CeCl 3 , the NQR resonance disappeared at 0.110 K and no lines were found above 0.054 K. In SmCl 3 , the NQR line disappeared at 0.21 K and no resonance was observed above 0.1 K. We have measured the internal field, which is proportional to the sublattice magnetization, at the chlorine nucleus in PrCl 3 and NdCl 3 below their Neel temperatures, and have determined the magnitude and the direction of the internal field at the chlorine nucleus relative to the principal axes of the electric field gradient.

Trends in Synthesis, Crystal Structure, and Thermal and Magnetic Properties of Rare-Earth Metal Borohydrides

“…There are few investigations of magnetism in metal borohydrides . The fairly large separation of magnetic ions and the ionic bonding in these materials suggests that weak exchange interactions and paramagnetism can be expected to low temperatures, similar to rare-earth di- and trihalides. − The ionic size of Br – ( r = 1.96 Å) is similar to that of the polyatomic BH 4 – ( r = 2.03 Å), but the BH 4 – unit may induce stronger crystal field effects, as shown below.…”

Low temperature cooperative behavior of the rare earth salts GdCl₃ and PrCl

“…The pair spectra results indicate an interaction 3+ between the Pr ions along the chain. Colwell, Mangum and Utton (1969) have measured the specific heat of PrClfrom 0.2 K to 4.0 K. They find a broad peak in the specific heat centered at 0.85 K which is consistent with a linear chain interaction. They also find a sharp peak at 0.4 K indicating the onset of long range ordering.…”

“…study in the three-dimensional ordered state to determine the type and symmetry of the low temperature phase. Figure 5.1 shows 35 the zero field quadrupole frequency of CI as a function of temperature (Colwell, Mangum and Utton, 1969). for the field parallel to C_, the X-axis of the electric field gradient tensor.…”

Electronic population effect in halogen nuclear spin - lattice relaxation in praseodymium trihalide compounds

“…The low-temperature properties of PrCl 3 , and to a lesser degree those of PrBr 3 , have been the subject of numerous investigations (Colwell et al 1969, Harrison et al 1976, Su et al 1991, Su and Armstrong 1993. Below 1 K, one-dimensional (1D) magnetic ordering occurs; this is followed by a phase transition at 0.4 K. The 1D behaviour is well described by an effective 1D XY Hamiltonian (Harrison et al 1976, Goovaerts et al 1984.…”