Ferromagnetism and heavy fermion semiconductor-like behavior in UFe0.6Sb2 single crystals

Abstract Single crystals of UFe 0.6 Sb 2 grown by Sb flux method have been investigated by means of X-ray diffraction, magnetic susceptibility, electrical resistivity and specific heat. UFe 0.6 Sb 2 crystallizes in the tetragonal HfCuSi 2 -type structure (space group P4/nmm). UFe 0.6 Sb 2 undergoes a ferromagnetic transition at T C  = 28 K with an easy axis along the c-axis. The resistivity resembles heavy fermion semiconducting-like behavior and implies three pseudogaps are formed in both directions. One pseudogap formed in the range of 9–30 K originates from states of impurity due to the partial occupancies of the Fe sites, and it can be closed by applying high magnetic field. The magnetic field, however, has little effects on the other two pseudogaps. A large electronic specific heat coefficient γ = 233 mJ/mol·K 2 reveals this compound is a strong electron correlation material.