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MA: Fachverband Magnetismus

MA 58: Computational Magnetism II

MA 58.4: Vortrag

Freitag, 13. März 2026, 10:15–10:30, POT/0151

Multi-spin Hamiltonians from symmetry considerations — •Levente Rózsa — HUN-REN Wigner Research Centre for Physics, Budapest, Hungary — Budapest University of Technology and Economics, Budapest, Hungary

Spin Hamiltonians are central to modeling magnetic materials. These Hamiltonians must reflect the symmetry of the underlying crystal [1]. Going beyond the most extensively studied two-spin interaction terms, for example the introduction of the isotropic biquadratic exchange interaction, has proven successful in describing special types of magnetic ordering in classical and quantum magnets. Four-spin generalizations of the anisotropic Dzyaloshinsky-Moriya interaction have also been proposed [2,3].

Here, we present a general formalism for deriving symmetry-adapted multi-spin interactions up to arbitrary order in the spin Hamiltonian. This method provides an alternative to perturbative expansions [2] which become difficult to tract as the number of spins and the complexity of the interactions increases. We identify all possible interaction terms containing four spins, and describe their transformation properties under rotations. We propose procedures for deriving these interactions from first-principles calculations, and for calculating the magnetic ground states stabilized by them.

[1] J. Bouaziz et al., Phys. Rev. B 112, 014406 (2025). [2] S. Brinker et al., New J. Phys. 21, 083015 (2019). [3] A. Lászlóffy, L. Rózsa et al., Phys. Rev. B 99, 184430 (2019).

Keywords: multi-spin interaction; spin Hamiltonian; Dzyaloshinsky-Moriya interaction