Specific heat and Hall effect of the ferromagnetic Kondo lattice UCu_0.9Sb₂

We have investigated the electrical resistivity ρ, specific heat C _p and Hall coefficient R _H on a single crystal of a ferromagnetic Kondo lattice UCu_0.9Sb₂. The experimental [Formula: see text], C _p (T) and [Formula: see text] data evidence a bulk magnetic phase transition at [Formula: see text] K, and additionally exhibit an unexpected bump located in the temperature range T _C/10-T _C/3. UCu_0.9Sb₂ has an enhanced electronic specific heat coefficient [Formula: see text] mJ molK^-2, corresponding to Kondo temperature [Formula: see text] K. An analysis of the Hall effect data for j//(a, b)-plane and H// c-axis reveals that the low-temperature ordinary Hall coefficient R ₀ is positive, suggesting that p-type electrical conductivity is dominant. The density of the carriers at 2 K is about 0.6 holes f.u.^-1, which may categorize the studied compound into class of low carrier density compounds. Combined γ and R ₀ data divulge an effective mass of charge carriers [Formula: see text] 27 m _e . This finding together with quite low Hall mobility [Formula: see text] cm² Vs^-1 and Kadowaki-Woods ratio [Formula: see text] [Formula: see text] cm (mol K² mJ^-1)², manifest the development of heavy-fermion state in the ferromagnetic UCu_0.9Sb₂ compound at low temperatures.