Matan, KittiwitGrohol, DanielYildirim, TanerNocera, Daniel G.Harris, A. BrooksLee, SeunghunNagler, Stephen E.Lee, Youngsu2023-05-232023-05-232006-06-232015-08-13https://repository.upenn.edu/handle/20.500.14332/43179The 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.PhysicsQuantum PhysicsArticle