ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
RCu2 compounds (R=rare earth) with orthorhombic crystal structures exhibit a rich variety of magnetic structures at low temperatures, originating from a subtle interplay between RKKY-type exchange and crystal field anisotropy. Though most of the magnetic properties of NdCu2 are well understood,1 there are controversial proposals for the magnetic phases, as deduced from different experiments.1,2 Therefore we have investigated the magnetic structure of NdCu2 by neutron diffraction as a function of temperature between 1.4 and 8 K in the zero external field. The diffraction patterns of a powdered sample were obtained on the multidetector DN5 at the SILOE reactor of CEN-G. Only two different magnetic phases were observed, in agreement with Ref. 1. For temperatures between 5.2 K and TN=6.5 K, the magnetic structure can be described by a sinusoidal oscillating component along b with wave vector τ2=(0.62, 0.042, 0). Accordingly, the structure is incommensurate with the lattice. Below 4.0 K the structure remains an oscillating component along b. However, the wave vector becomes commensurate with the lattice and is given by τ1=(0.60, 0, 0). Additionally, a progressive squaring up from the appearance of the third harmonic 3τ in the range from 4.0 K down to 1.4 K is observed. At 1.4 K the amplitudes of the fundamental and the third harmonic are 2.4μB and 0.9μB, respectively. Around 4.4 K, the spectra seem to be determined by a superposition of the high- and low-temperature phases. The low-temperature structure of NdCu2 is comparable with that for TmCu2, observed earlier in Ref. 3. Though in that work a different interpretation was chosen, the wave vector of the fundamental oscillation can be described by (0.625, 0, 0), while the amplitudes for the fundamental and third harmonic are given by 8.0μB and 2.6μB, respectively.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.356909
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