Matan, KittiwitGrohol, DanielYildirim, TanerNocera, Daniel G.Harris, A. BrooksLee, Seunghun H.Nagler, Stephen E.Lee, Young S2023-05-232023-05-232006-06-192011-07-14https://repository.upenn.edu/handle/20.500.14332/42887The spin wave excitations of the S = 5/2 kagomé lattice antiferromagnet KFe3(OH)6(SO4)2 have been measured using high-resolution inelastic neutron scattering. We directly observe a flat mode which corresponds to a lifted ‘‘zero energy mode,’’ verifying a fundamental prediction for the kagomé lattice. A simple Heisenberg spin Hamiltonian provides an excellent fit to our spin wave data. The antisymmetric Dzyaloshinskii-Moriya interaction is the primary source of anisotropy and explains the low-temperature magnetization and spin structure.Physical Sciences and MathematicsPhysicsArticle