Structural effects on the magnetic properties of FePd and FeRh

The magnetic structures of the ordered transition-metal compounds FePd and FeRh are found in both the CsCl and CuAu atomic structures by first-principles total-energy calculations. The ground state of FePd is shown to be the CuAu structure and ferromagnetic, in agreement with experiment. However, at equilibrium in the CsCl structure, where FePd is metastable, FePd behaves just like FeRh and has an antiferromagnetic ground state. A ferromagnetic phase of FePd lies 0.5 mRy higher in energy at the equilibrium volume and, like FeRh, but more readily, undergoes a first-order phase transition from the antiferromagnetic phase to the ferromagnetic phase at an expanded lattice constant or in a magnetic field. © 1993 The American Physical Society.