Volume dependence of the magnetic phases of ordered FeCr

The magnetic phase structure of FeCr in the CsCl (Formula presented) structure is studied as a function of volume by first-principles calculations using a four-atom unit cell. The ground state is found to be ferromagnetic (FM), but at a 3% expansion of the lattice constant the ground state becomes type-I antiferromagnetic (AF). The AF phase has the unusual structure in that both Fe and Cr sublattices are separately type-I AF. In both the FM and AF phases the Fe moment is reduced from that in pure bcc Fe and the Cr moment increased from that in pure bcc Cr. © 1998 The American Physical Society.