Antiferromagnetism in face-centered-tetragonal iron

Abstract

The total energy of face-centered-tetragonal iron is calculated within density- functional theory. We have obtained results for nonmagnetic, ferromagnetic, and antiferromagnetic iron. In the range of tetragonal structures we have studied, our total- energy calculations for the ferromagnetic phase give just two minima: One is nearly bcc (c/a=0.71) and one is nearly fcc (c/a=1). The antiferromagnetic phase yields only one minimum near the fcc structure, but is unstable near the bcc structure. The global minimum in total energy is antiferromagnetic. The difference in total energy between ferromagnetic and antiferromagnetic iron shows an oscillatory behavior as a function of c/a. Our results show that it might be possible to grow iron films with a large in-plane lattice constant that have an antiferromagnetic ordering.