Anisotropic electrical resistivity of the magnetic heavy-fermion superconductor URu2Si2

Electrical-resistivity measurements ρ(T,H) on single-crystal URu2Si2 have been performed between 0.3 and 300 K in fields up to 7 T. ρ(T) is highly anisotropic with the 300-K values parallel to the a and c axes differing by a factor of 2. Both directions exhibit a dρ/dT < 0 down to 80 K, followed by a steep decrease in ρ below 50 K. An upper antiferromagnetic transition is clearly discerned by a “Cr-like” anomaly at ≈17 K which also marks the onset of a strong, positive ρ(H). Below 4 K, ρ(T) is isotropic and goes to zero at the superconducting transition TC = 0.8 K.