First-order magnetic phase transition in PrCo9Si4 and NdCo9Si4

Abstract The tetragonal compounds PrCo 9 Si 4 and NdCo 9 Si 4 have been studied by specific heat, electrical resistivity and magnetic susceptibility measurements. The onset of ferromagnetic order is observed at Curie temperatures T C ≃24 and 12 K for PrCo 9 Si 4 and NdCo 9 Si 4 , respectively. Thermodynamic and transport data of both compounds reveal a first-order phase transition from the paramagnetic to the ferromagnetic state which can be deduced from step like anomalies in the resistivity data as well as sharp peak-type anomalies of the specific heat.