Noncollinear order in the γ-Fe system: Generalized Heisenberg approach
2006 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 73, no 10, 104443- p.Article in journal (Refereed) Published
We investigate the complex magnetic ordering in face-centered cubic (fcc) Fe (γ-Fe) using a mapping of the electronic structure problem to an effective Heisenberg model via Green's function perturbation theory. We find that low-moment ([approximate]0.6µB) spin spirals (SSs) are accurately captured by this Hamiltonian, but not SSs of intermediate-moment ([approximate]2.0µB). We attribute this latter result to a hybridization gap at the Fermi level, resulting from the specific symmetry of the SS, which is difficult to capture within a perturbative approach. Using a generalization of the usual Heisenberg approach, in which we include the moment size as well as orientational degrees of freedom, we find that the strong volume dependence of this system enters through the intrasite exchange term only. We confirm this result with direct calculations of fixed moment and relaxed moment spin spirals. This highlights the importance of intrasite magnetism in this system, and points toward the moment and not the volume as being the crucial quantity to compare with experiments.
Place, publisher, year, edition, pages
American Physical Society , 2006. Vol. 73, no 10, 104443- p.
Iron, ferromagnetic materials, Heisenberg model, Green's function methods, magnetic moments, Fermi level
IdentifiersURN: urn:nbn:se:liu:diva-14276DOI: 10.1103/PhysRevB.73.104443OAI: oai:DiVA.org:liu-14276DiVA: diva2:23070