Effect of Non-Heisenberg Magnetic Interactions on Defects in Ferromagnetic Iron

Effect of Non-Heisenberg Magnetic Interactions on Defects in Ferromagnetic Iron

Effect of Non-Heisenberg Magnetic Interactions on Defects in Ferromagnetic Iron 150 150 UKAEA Opendata
UKAEA-CCFE-PR(23)86

Effect of Non-Heisenberg Magnetic Interactions on Defects in Ferromagnetic Iron

Fundamental flaws in the Heisenberg Hamiltonian are highlighted in the context of its application to BCC Fe, including the particular issues arising when modelling lattice defects. Exchange integrals are evaluated using the magnetic force theorem. The bilinear exchange coupling constants are calculated for all the interacting pairs of atomic magnetic moments in large simulation cells containing defects, enabling a direct mapping of the magnetic energy onto the Heisenberg Hamiltonian. We provide a simple procedure for extracting Landau parameters from DFT calculations, to construct a Heisenberg-Landau Hamiltonian. We quantitatively show how the Landau terms correct the exchange-energy hypersurface, which is essential for the accurate evaluation of energies of defects.

Collection:
Journals
Journal:
Physical Review B
Publisher:
APS (American Physical Society)
Published date:
21/12/2020