Y{0.5}$Ca{0.5}BaCo4O7 contains kagome layers of Co ions, whose spins are strongly coupled according to a Curie-Weiss temperature of -2200 K. At low temperatures, T = 1.2 K, our diffuse neutron scattering study with polarization analysis reveals characteristic spin correlations close to a predicted two-dimensional coplanar ground state with staggered chirality. The absence of three dimensional long-range AF order proves negligible coupling between the kagome layers. The scattering intensities are consistent with high spin S=3/2 states of Co2+ in the kagome layers and low spin S=0 states for Co3+ ions at interlayer sites. Our observations agree with previous Monte Carlo simulations indicating a ground state of only short range chiral order.
@article{arxiv.cond-mat/0607238,
title = {Approaching the ground state of the kagome antiferromagnet},
author = {W. Schweika and M. Valldor and P. Lemmens},
journal= {arXiv preprint arXiv:cond-mat/0607238},
year = {2015}
}