Ferromagnetism in the orthorhombic PrPd and SmPd

Highlights: • The magnetic behavior of PrPd and SmPd has been investigated. • PrPd and SmPd compounds order ferromagnetically with T_C of 12 and 22 K, respectively. • Magnetization, heat capacity and electrical resistivity have been measured. • Evidence for a gapped magnon spectrum in the ordered state of both compounds is observed. • A rather large coercive field of 12 kOe is observed at 2 K for SmPd. In continuation of our studies on the binary RPd compounds (orthorhombic CrB-type structure, Pearson symbol oS8, space group Cmcm, No. 63), we report here the magnetic properties of the iso-structural PrPd and SmPd. The two compounds order ferromagnetically with the Curie temperature, T_C, of nearly 12 K and 22 K, respectively (inferred from the peak temperature of the heat capacity at the paramagnetic to ferromagnetic transition). Anomalies in the magnetization and the electrical resistivity are also observed in correspondence of the bulk magnetic transition. The ferromagnetic nature of the magnetic transition is clearly indicated by the temperature and field dependence of the magnetization. The coercive fields of the two compounds are measured to be 160 Oe and 12 kOe at 2 K, respectively. The temperature dependence of both the heat capacity and electrical resistivity indicates a gapped ferromagnetic magnon spectrum with the gaps of ≈11 K and ≈40 K in PrPd and SmPd, respectively. The data obtained in current work are compared and discussed together with those previously reported for CePd and NdPd; the Curie temperatures of the four RPd iso-structural compounds follow the de Gennes scaling.