Magnetic, electrical transport, and thermal properties of a uranium intermetallic compoundUCu5In

Abstract

A ternary intermetallic compound UCu 5 In has been studied by means of magnetization, electrical resistivity, magnetoresistivity, thermopower, thermal conductivity, heat-capacity, and thermal-expansion measurements. The experimental findings reveal UCu 5 In to be antiferromagnetically ordered (T N ϭ25 K) dense Kondo system (T K ϭ24 K) with a considerable enhancement of the effective mass of conduction electrons at low temperatures, yielding the Sommerfeld coefficient ␥(0) of about 240 mJ/͑mole K 2 ). Although the electrical resistivity and the thermopower of UCu 5 In shows features characteristic of interplay of Kondo and crystal-field effects, the magnetoresistivity does not exhibit behavior expected for Kondo systems being large and positive even well above T N . Consistent explanation of the latter results is attempted by considering the role of magnetic precursor effects and/or interfacelike effects due to the presence of nonmagnetic layers.

Crystal structure and physical properties of a novel Kondo antiferromagnet: U3Ru4Al12

“…These variations are expected for a Kondo compound in the presence of crystal electrical field effects [20,21], in agreement with magnetic, electrical resistivity and magnetoresistivity properties. Almost identical behaviour has been previously observed for UCu 5 In [22] which crystallizes in an orthorhombic structure and being also an antiferromagnet with T N = 25 K. The change in sign observed for these two compounds at temperatures close to their T N can be attributed to a change in the density of states near the Fermi level due to a reconstruction of the Fermi surface. The sign change of thermopower (TEP) in the semi-phenomenological model [23] can be ascribed to the development of magnetic correlations at low temperature.…”

10.1007/s11451-008-1001-8

“…Some metallic solids (as well as some metallic compositions [24], CeAl 3 [25], CeCu 2 Si 2 [26], UCu 5 In [27]) at low temperatures, however, follow the dependence κ ph ~ T. Theoretical calculations [24] suggest that such a temperature dependence κ ph (T) can occur at low temperatures in metallic materials in which ρ 0 > 10 µΩ cm, and the phonon wavelength in this temperature range becomes comparable to or larger than the mean free path length of carriers. It is this situation that probably is realized in our case with κ ph for the LuMgCu 4 sample, which features, as mentioned above, ρ 0 = 13.2 µΩ cm.…”

Heavy-fermion characteristics inUCu5Alsingle crystals

“…[1][2][3] All these compounds show interesting physical properties, for instance, the Sommerfeld ratio C p /T of each of them increases with decreasing temperature, reaching values of the order 200 mJ/K 2 mole U at 1 K. However, the physical properties of these compounds have been studied on polycrystalline samples only. In order to elucidate the observed properties we have undertaken investigations on single-crystalline samples.…”