2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/20525The properties of the groundstate and first excitations of 2dimensionnal quantum antiferromagnets are rapidly sketched. A special emphasis is put on the gapped phases: Valence Bond Crystals and the two types of Spin Liquids. New results on the spin susceptibility of small samples of the Heisenberg antiferromagnet on a kagomé lattice are displayed for comparison with Kagemaya {\it et al.} experimental result (this conference).7 pages, 4 figures, Proceedings of French-Japanese Symposium on "Quantum Properties of Low-Dimensional Antiferromagnets", held in Fukoaka, Japan, November 20-22, 2001Strongly Correlated Electronstext