A new family of heavy-fermion compounds: U4TGa12 (T = Fe, Co, Rh and Pd)

U4TGa12 (T = Fe, Co, Rh and Pd) compounds represent a new family of isostructural heavy-fermion materials. They crystallize in the cubic structure type Y4PdGa12 (Im3¯m) which consists of the doubling of the UGa3 (AuCu3-type, Pm3¯m) elementary cell with a partial ordered occupancy (1/4) of the gallium octahedra by the transition metal atoms. Their magnetic and electronic properties (resistivity, magnetization and specific heat) have been investigated. All compounds display a moderately enhanced value of the Sommerfeld coefficient γ (80–140 mJ/mol U K2) whereas only U4PdGa12 shows the occurrence of an antiferromagnetic order below TN = 43 K.