title: Field induced ordering in highly frustrated antiferromagnets.
abstract: We predict that an external field can induce a spin ordering in highly frustrated classical Heisenberg magnets. We find analytically stabilization of collinear states by thermal fluctuations at a one-third of the saturation field for kagome and garnet lattices and at a half of the saturation field for pyrochlore and frustrated square lattices. This effect is studied numerically for the frustrated square-lattice antiferromagnet by Monte Carlo simulations for classical spins and by exact diagonalization for S = 1/2. The field induced collinear states have a spin gap and produce magnetization plateaus.
authors.affiliation: Theoretische Physik, ETH Hönggerberg, CH-8093 Zürich, Switzerland.
authors.forename: M E
authors.initials: ME
authors.lastname: Zhitomirsky
authors.forename: A
authors.initials: A
authors.lastname: Honecker
authors.forename: O A
authors.initials: OA
authors.lastname: Petrenko