Order versus Disorder in the Quantum Heisenberg Antiferromagnet on the Kagomé lattice: an approach through exact spectra analysis

الأصل · EN

A group symmetry analysis of the low lying levels of the spin-1/2 kagomé Heisenberg antiferromagnet is performed for small samples up to N=27. This approach allows to follow the effect of quantum fluctuations when the sample size increases. The results contradict the scenario of ``order by disorder'' which has been advanced on the basis of large S calculations. A large enough second neighbor ferromagnetic exchange coupling is needed to stabilize the √ 3 × √ 3 pattern: the finite size analysis indicates a quantum critical transition at a non zero coupling.