Ab initio study of the Fe intra- and inter-layer magnetic order in Fe/Ir(001) superlattices
IPCMS-Gemm (UMR 7504 du CNRS), 23 rue du Loess, 67034 Strasbourg, France
Corresponding author: a email@example.com
Revised: 1 December 2003
Published online: 2 April 2004
An ab initio study of the magnetic behaviour of strained Fe/Ir(001) superlattices is presented using the first principle Augmented Spherical Wave method. First, the intralayer magnetic order of the Fe layers is examined as a function of their tetragonal distortion induced by the superlattice structure. It is shown that (i) an antiferromagnetic order can not occur, (ii) a ferrimagnetic phase, characterized by interfacial Fe magnetic moments opposite to the others, is allowed in a large domain of distortions, (iii) first order transitions toward the ferromagnetic (non magnetic) phase occur when the tetragonal distortion is (respectively) reduced at constant atomic volume (in plane lattice parameter) and (iv) when the Fe thickness increases, the ferromagnetic/ferrimagnetic transition is shifted to higher tetragonal distortions. Second, the interlayer magnetic couplings are determined in Fe5Ir superlattices with the Fe layer in the relaxed body centered cubic structure with n=1 to 11 monolayers. It is shown that the coupling energy decreases surprisingly slowly (like 1/n) with increasing n with a period of approximately 3.2 monolayers, which corresponds nicely to the period of the Ir induced polarisation. Finally, these results are discussed in relation with experimental studies.
PACS: 75.30.Et – Exchange and superexchange interactions / 75.70.-i – Magnetic properties of thin films, surfaces, and interfaces / 75.70.Cn – Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2004