Physical properties of the ferromagnetic heavy-fermion compound U Ir2 Zn20

Measurements of magnetization, specific heat, neutron diffraction, and electrical resistivity at ambient and applied pressure have been carried out on the cubic compound U Ir2 Zn20. A first-order-like ferromagnetic transition occurs at TC =2.1 K with a saturation magnetization μsat ∼0.4 μB, indicating itinerant ferromagnetism. In this ordered state, the electronic specific heat coefficient remains large, γ∼450 mJmol K2, classifying U Ir2 Zn20 as one of the very few heavy-fermion ferromagnets.