Competing Magnetic Phases on a "Kagome Staircase"
  We present thermodynamic and neutron data on Ni_3V_2O_8, a spin-1 system on a kagome staircase. The extreme degeneracy of the kagome antiferromagnet is lifted to produce two incommensurate phases at finite T - one amplitude modulated, the other helical - plus a commensurate canted antiferromagnet for T ->0. The H-T phase diagram is described by a model of competing first and second neighbor interactions with smaller anisotropic terms. Ni_3V_2O_8 thus provides an elegant example of order from sub leading interactions in a highly frustrated system 
G. Lawes, M. Kenzelmann, N. Rogado, K. H. Kim, G. A. Jorge, R. J.   Cava, A. Aharony, O. Entin-Wohlman, A. B. Harris, T. Yil...