Háskóli ÍslandsUniversity of IcelandSzilva, A.Thonig, D.Bessarab, PavelKvashnin, Y. O.Rodrigues, D. C. M.Cardias, R.Pereiro, M.Nordström, L.Bergman, A.Klautau, A. B.Eriksson, O.2018-01-252018-01-252017-10-10Szilva, A., Thonig, D., Bessarab, P. F., Kvashnin, Y. O., Rodrigues, D. C. M., Cardias, R., . . . Eriksson, O. (2017). Theory of noncollinear interactions beyond Heisenberg exchange: Applications to bcc Fe. Physical Review B, 96(14), 144413. doi:10.1103/PhysRevB.96.1444132469-99502469-9969 (eISSN)https://hdl.handle.net/20.500.11815/539We show for a simple noncollinear configuration of the atomistic spins (in particular, where one spin is rotated by a finite angle in a ferromagnetic background) that the pairwise energy variation computed in terms of multiple-scattering formalism cannot be fully mapped onto a bilinear Heisenberg spin model even in the absence of spin-orbit coupling. The non-Heisenberg terms induced by the spin-polarized host appear in leading orders in the expansion of the infinitesimal angle variations. However, an E g − T 2 g symmetry analysis based on the orbital decomposition of the exchange parameters in bcc Fe leads to the conclusion that the nearest-neighbor exchange parameters related to the T 2 g orbitals are essentially Heisenberg-like: they do not depend on the spin configuration, and can, in this case, be mapped onto a Heisenberg spin model even in extreme noncollinear cases.144413eninfo:eu-repo/semantics/openAccessFerromagnetismNoncollinear magnetsDensity functional theoryHeisenberg modelSegulmagnBylgjufræðiSkammtafræðiinfo:eu-repo/semantics/articlePhysical Review B10.1103/PhysRevB.96.144413