Heavy-electron-like behavior in cubic PrCu₄Au

The magnetization M(H), magnetic susceptibility χ(T), electrical resistivity ρ(T) and specific heat C(T) properties of PrCu₄Au have been investigated. A clear antiferromagnetic transition T_N is observed at 2.5K in C(T) and χ(T). The internal magnetic field at the Pr nucleus, H_HF, is obtained to be 195T from the nuclear specific heat observed in C(T) below 0.7K. The ground state of Pr 4f² in the cubic crystalline electric field is inferred to be a magnetic triplet Γ₅ from the magnitude of the magnetization at 2K, which coincides with the value of the 4f² magnetic moments deduced from H_HF. The large value of the electronic specific heat coefficient, γ, remains at the zero-temperature limit even in external magnetic fields. On the other hand, the entropy up to T_N is somewhat less than Rln3. These anomalous heavy-electron-like behaviors probably originate in the fact that both the magnetic moments and the quadrupole moments are involved in the ground state of Pr4f².