title: Fermionic spin excitations in two- and three-dimensional antiferromagnets.
abstract: Spin excitations in an ordered Heisenberg magnet are magnons-bosons with spin 1. That may change when frustration and quantum fluctuations suppress the order and restore the spin-rotation symmetry. We show that spin excitations in the S=1/2 Heisenberg antiferromagnet on a kagome lattice are spinons-fermions with spin 1/2. In the ground state the system can be described as a collection of small, heavy pairs of spinons with spin 0. A magnetic excitation of lowest energy amounts to breaking up a pair into two spinons at a cost of 0.06 J.
authors.affiliation: Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland, USA.
authors.forename: Zhihao
authors.initials: Z
authors.lastname: Hao
authors.forename: Oleg
authors.initials: O
authors.lastname: Tchernyshyov