Spinon deconfinement above a finite energy gap in 2d Quantum Heisenberg   Antiferromagnets
  The familiar spin-1/2 quantum Heisenberg antiferromanget in a 2d square lattice is shown, within the non linear sigma model approximations, to be another novel state of matter that has excitations with fractional quantum numbers above a finite energy gap. 1-skyrmion with an energy $\approx 2\pi J$ is shown to be made of two `deconfined spinons' or `SU(2) vortices'. The many skyrmion operator and the wave functions that we have found are strikingly similar to quantum Hall quasi particle operators and wave functions. We also predict the presence of finite energy `spin-S spinon' for a general spin-S Heisenberg antiferromagnets in 2d. Some consequences are briefly discussed. 
G. Baskaran (Inst. Math. Sci., Madras)