LAUSR

abstract The structure, magnetic and electronic properties of the quaternary Heusler alloy CoFeCrAl in bulk and the (001)-, (110)- and (111)-oriented thin films have been studied by spin-polarized first-principles calculations. The results show that, for the CoFeCrAl (001)-oriented thin films the half-metallic (HM) character of the bulk CoFeCrAl alloy is maintained in the CrCr* slab, but lost in the CoFe, CoCo* and FeFe* slabs, the CrAl and AlAl* slabs are nearly half-metals. The AlAl* slab with the lowest surface energy is the most stable, while the CrAl and CrCr* slabs are the second and third most stable slabs, respectively. The HM character of the bulk CoFeCrAl alloy is lost in the natural CoFeCrAl slab of the (110)-oriented thin film and the natural CoCo, FeFe, CrCr and AlAl slabs of the (111)-oriented thin films.