Magnetic Structure and Spin Waves in the Kagom\'{e} Jarosite compound ${\bf KFe_3(SO_4)_2(OH)_6}$

TL;DR

This study investigates the magnetic structure and spin wave excitations in the Fe jarosite compound, revealing that Dzyaloshinskii-Moriya interactions dominate anisotropy and accurately explain experimental neutron scattering data.

Contribution

It provides a comprehensive analysis of the magnetic interactions in Fe jarosite, highlighting the dominance of Dzyaloshinskii-Moriya interactions in explaining spin-wave spectra and spin canting.

Findings

Dzyaloshinskii-Moriya interactions are the main anisotropic interactions.

The model accurately reproduces neutron scattering spin-wave data.

Spin canting out of the Kagomé plane is explained by DM interactions.

Abstract

We present a detailed study of the magnetic structure and spin waves in the Fe jarosite compound ${\rm KFe_3(SO_4)_2(OH)_6}$ for the most general Hamiltonian involving one- and two-spin interactions which are allowed by symmetry. We compare the calculated spin-wave spectrum with the recent neutron scattering data of Matan {\it et al.} for various model Hamiltonians which include, in addition to isotropic Heisenberg exchange interactions between nearest ($J_1$) and next-nearest ($J_2$) neighbors, single ion anisotropy and Dzyaloshinskii-Moriya (DM) interactions. We concluded that DM interactions are the dominant anisotropic interaction, which not only fits all the splittings in the spin-wave spectrum but also reproduces the small canting of the spins out of the Kagom\'e plane. A brief discussion of how representation theory restricts the allowed magnetic structure is also given.