Theory of noncollinear interactions beyond Heisenberg exchange: Applications to bcc Fe

A. Szilva, D. Thonig, Pavel Bessarab, Y. O. Kvashnin, D. C. M. Rodrigues, R. Cardias, M. Pereiro, L. Nordström, A. Bergman, A. B. Klautau, O. Eriksson

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)


We 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.
Original languageEnglish
Number of pages144413
JournalPhysical Review B
Issue number14
Publication statusPublished - 10 Oct 2017

Other keywords

  • Ferromagnetism
  • Noncollinear magnets
  • Density functional theory
  • Heisenberg model
  • Segulmagn
  • Bylgjufræði
  • Skammtafræði


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