Berlin 2018 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 38: Theory of strongly correlated systems
MA 38.8: Vortrag
Donnerstag, 15. März 2018, 11:45–12:00, H 0110
Theory of noncollinear interactions beyond Heisenberg exchange: Applications to bcc Fe — •Attila Szilva1, Danny Thonig1, Pavel Bessarab2, Yaroslav Kvashnin1, Debora Rodrigues3, Ramon Cardias1, Manuel Pereiro1, Lars Nordström1, Anders Bergman1, Angela Klautau3, and Olle Eriksson1 — 1Department of Physics and Astronomy, Division of Materials Theory, Uppsala University, Box 516, SE-75120 Uppsala, Sweden — 2Science Institute of the University of Iceland, 107 Reykjavik, Iceland and Department of Nanophotonics and Metamaterials, ITMO University, 197101 St. Petersburg, Russia — 3Faculdade de Física, Universidade Federal do Pará, Belém, 66075-110, Brazil
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 Eg-T2g 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 T2g 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.
DOI: 10.1103/PhysRevB.96.144413