Thickness stabilization of ferromagnetic order of FeGe2 compounds

Electronic and magnetic properties of ultra-thin films of FeGe2 compounds have been investigated using ab initio density functional theory (DFT). In the bulk environment we obtained anti-ferromagnetic coupling between Fe atoms and no magnetic polarization on Ge atoms. Besides this ground state configuration a metastable solution is obtained with a ferromagnetic coupling between Fe atoms and anti-ferromagnetic coupling between Fe and Ge. Concerning the thin films, the magnetic coupling between Fe atoms depends on the film thickness. Ferromagnetic order is obtained in the case of an ultra-thin film and a transition to anti-ferromagnetic coupling is observed when we increase the film thickness.