Antiferromagnetic structure of UNiAl
Résumé
UNiAl crystallizes in the hexagonal ZrNiAl-type structure. Magnetic, transport, and thermal properties of
UNiAl point to an antiferromagnetic ~AF! ordering below T N519.3 K. Below this temperature UNiAl orders
with propagation vector q5(0.1,0.1,0.5). U magnetic moments are oriented along the hexagonal axis and
modulated sinusoidally within the basal plane. The modulation is not even partially squared-up down to 1.7 K.
The maximum size of U moment is (1.2460.03)
mB /U. However, the three U atoms that are crystallographi-
cally equivalent do not carry the same moment within the crystallographic unit cell. The propagation vector of
AF structure does not change in the whole temperature range. AF correlations that propagate also with q
5(0.1,0.1,0.5) can be traced at temperatures up to 30 K showing the critical scattering near T N .