H. Nakotte et al., NON-FERMI-LIQUID SCALING IN HEAVY-FERMION UCU3.5AL1.5 AND UCU3AL2, Physical review. B, Condensed matter, 54(17), 1996, pp. 12176-12183
We report on specific-heat, magnetic-susceptibility, high-field-magnet
ization, electrical-resistivity, and neutron-diffraction results on UC
u3.5Al1.5 (polycrystal) and UCu3Al2, (polycrystal and single crystal).
Our results indicate that both compounds crystallize in the hexagonal
CaCu5 structure with ordered UCu2 planes separated by planes containi
ng a statistical distribution of Al along with the remaining Cu atoms.
At low temperatures, the specific heat and the magnetic susceptibilit
y of both compounds are enhanced, but their temperature dependences ar
e found to be distinct from expectations of Fermi-liquid theory. UCU3.
5Al1.5 does not order magnetically, and the low-temperature specific h
eat and magnetic susceptibility show scaling behavior (C/T proportiona
l to ln T and chi proportional to T--1/3) reminiscent of non-Fermi-liq
uid materials. For UCu3Al2, on the other hand, the low-temperature sca
ling of bulk properties is masked by an anomaly around 8-10 K, which i
s presumably of magnetic origin. Single-crystal studies of UCu3Al2 rev
eal a huge magnetic anisotropy with very different in-plane response c
ompared to the c-axis response. Our data provide evidence that any tem
perature dependence of the magnetic susceptibility (and electrical res
istivity) of polycrystalline material may be due to averaging anisotro
pic response over all crystallographic directions. The results are dis
cussed in the context of findings from other non-Fermi-liquid material
s.