Phase diagram of the SmCo1−xFexAsO system

A series of SmCo1−xFexAsO (x = 0, 0.05, 0.1, 0.2, 0.3) polycrystalline samples were synthesized and their transport and magnetic properties were studied. Similar to the undoped SmCoAsO, these Fe-doped samples of SmCo1−xFexAsO also undergo successive magnetic phase transitions associated with the Co or Fe magnetic moments below 100 K, i.e., the system become ferromagnetic (FM) ordered first below the Curie temperature Tc and then become antiferromagnetic (AFM) ordered with further decreasing temperature. With Fe doping on the Co site, both FM (Tc) and AFM (TN1) transition temperatures are rapidly suppressed and then both Tc and TN1 approaching zero temperature at x = 0.3, whereas the AFM order (TN2) of Sm3+ moments below 5.1 K is still robust. Based on these results, the magnetic phase diagram in the Co-rich side of the SmCo1−xFexAsO system is established.