The quasi-one-dimensional character of spin waves in K₂Fe₇Se₈

Abstract

The ground state phase diagram, the physical properties of spin waves and the dynamic structure factor of the new family of 122 iron-vacancy ordered compound K 2 Fe 7 Se 8 are theoretically investigated based on the J 1 -J 2 Heisenberg model. Four antiferromagnetic phases are found to be stable in the reasonable physical parameter region. The dispersion relations of the spin waves for the newly discovered AFM2 and AFM3 phases are studied using the linearized spin wave theory. Two acoustic spin wave branches and 12 optical spin wave branches are present in both the AFM2 and AFM3 phases, and each of them are twofold degenerate. One more interesting finding is that the spin waves of K 2 Fe 7 Se 8 have the quasi-one-dimensional character at the high frequency range. To offer theoretical guidance for the further neutron scattering experiments, the inelastic neutron scattering patterns for the AFM2 and AFM3 phases are also investigated.

Topological magnons in one-dimensional ferromagnetic Su–Schrieffer–Heeger model with anisotropic interaction

“…We notice that different from our local spins, topological magnons in 1D itinerant flatband ferromagnet are also proposed 46 . Indeed, the 1D topological magnons can be explored in realistic one-dimensional (1D) magnets 47 , quasi-1D magnetic materials 48 , or 1D organic magnetic systems 49,50 . As can be expected, more 1D magnetic models rather than the SSH model can be extended to topological magnons.…”