Complex magnetic ordering in the noncentrosymmetric metal PrCuGe₃

We report on the successful synthesis of PrCuGe₃ which crystallizes in the tetragonal BaNiSn₃-type structure (space group: I4mm) with lattice parameters, a = 4.1470(2) Å and c = 10.185(3) Å. The material is characterized using dc magnetic susceptibility χ(T), ac magnetic susceptibility χ_ac(T), isothermal magnetization M(B), specific heat C_p(T), and electrical resistivity ρ(T) measurements. PrCuGe₃ undergoes a long-range ferromagnetic ordering at T_C = 23 K, which is followed by another transition below T_tr = 17 K. T_C has a quite small anomaly in C_p(T) and ρ(T) despite displaying large associated anomalies in both χ(T) and χ_ac(T) and a sizable ferromagnetic ordered moment. Instead the transition at T_tr has a much larger anomaly in C_p(T) and ρ(T) but essentially no signal in χ(T) and χ_ac(T). Such observations in PrCuGe₃ are nontrivial. A Sommerfeld coefficient γ = 375 mJ/(mol K²) is extracted from specific heat which indicates a significant enhancement of the quasi-particle mass at low temperature. Hence, PrCuGe₃ exemplifies a system with the coexistence of complex magnetic ordering and a putative heavy-fermion state.