Laboratoire de Physique Théorique
Toulouse - UMR 5152

We consider kagome and triangular lattice magnets with strong easy axis single-ion anisotropy and antiferromagnetic exchange . When , the low energy states selected by the anisotropy map on to configurations of the corresponding classical Ising antiferromagnet. Sub-leading multi-spin interaction arising from the transverse quantum dynamics makes the low temperature behaviour very different from the well-known classical case : The kagome magnet goes into a semiclassical spin liquid state with distinctive and unusual short-range correlations below a crossover temperature , while the triangular magnet undergoes a first-order transition at to an orientationally ordered collinear state that gives rise to a novel zero-magnetization plateau for small magnetic fields along the easy axis. Possible experimental implications are also discussed.