Ordering Phenomena in Transition Metal Oxides

Spinon pairs in the S=1/2 Heisenberg model on kagome   

We show that a S=1/2 Heisenberg antiferromagnet on kagome has a finite concentration of spinons in the ground state. Spinons are fermionic quasiparticles with spin 1/2 interacting with an emergent compact U(1) gauge field, whose electric field lines represent valence bonds. Exchange-mediated attraction binds spinons into small, heavy pairs with spin 0. Low-energy spin excitations correspond to breaking up a pair into two free spinons. Our estimates of the ground-state energy and the spin gap compare favorably with existing numerical results.

Work done in collaboration with Zhihao Hao (Johns Hopkins University).