Hill Plot Focusing on Ce Compounds with High Magnetic Ordering Temperatures and Consequent Study of Ce{sub 2}AuP{sub 3}

The Hill plot is a well-known criterion of the f-electron element interatomic threshold distance separating the nonmagnetic state from the magnetic state in actinides and lanthanides. We have reinvestigated the Hill plot of Ce compounds using the commercial crystallographic database CRYSTMET, focusing on a relationship between the Ce-Ce distance and the magnetic ordering temperature because a Ce compound with no other magnetic elements rarely has a magnetic ordering temperature that is higher than 20 K. The Hill plot of approximately 730 compounds has revealed that a Ce compound, particularly a ferromagnet, showing a high magnetic ordering temperature would require a short Ce-Ce distance with a suppression of the valence instability of the Ce ion. From the study, we developed interest in Ce{sub 2}AuP{sub 3} with a Curie temperature of 31 K. The ferromagnetic nature of this material has been examined in terms of a doping effect, which suggests a possible increase in magnetic anisotropy energy.