Magnetic and transport properties of new ternary uranium-based germanide U₂Rh₃Ge₅

A new ternary uranium germanide U2Rh3Ge5 has been successfully synthesized and investigated by means of magnetic susceptibility χ(T, H), isothermal magnetization M(T, H), electrical resistivity ρ(T), and specific heat C(T, H) measurements. This compound is found to crystallize in the U2Co3Si5-type orthorhombic structure. The low-field χ(T) shows a clear peak at T N = 41.5 K corresponding to an antiferromagnetic transition. The M(H) curve measured up to 71 kOe exhibits an H-linear behavior at 2 K with very small induced magnetic moments, while it shows upward curvature with increasing temperature, implying the possible presence of a metamagnetic transition in high-field region above 71 kOe. As the temperature decreases, ρ(T) increases slowly at T > T N and decreases rapidly at T < T N, which can be understood based on a semiconductor-like narrow band gap model (or the c-f hybridization effect) and an antiferromagnetic spin-wave model, respectively. No evidence of heavy-fermion behavior or superconductivity transition is observed at temperatures as low as 1.4 K. The obtained experimental results are discussed by comparing with those reported for the isomorphic compound U2Ir3Si5 and the quasi-isomorphic compound U2Rh3Si5.