Electrical transport in URu2Si2

The temperature dependence of the resistivity, magnetic susceptibility and Hall coefficient have been measured in oriented single-crystals of URu2Si2. The susceptibility is Curie-Weiss like at high temperatures and the anisotropy shows that the f moments on the U atoms are highly confined to lie along the c direction. The resistivity is analysed in terms of a Kondo-like behaviour at high temperatures and shows the onset of coherence, modified by electron-spin wave scattering, at low temperatures. There is a sharp superconducting transition at 1.33 K. The Hall coefficient is analysed by using a modification of the recent theory by Fert and Levy and suggests that the coherence temperature T0 and the Kondo temperature Tk need not be sharply distinguished in URu2Si2. There is a large increase in the Hall coefficient as the temperature is lowered below 18 K which is attributed to a Fermi surface restructuring, possibly due to the existence of spin density waves in the antiferromagnetic state. (author)