Vortex dynamics and frustration in two-dimensional triangular chromium lattices

The spin dynamics of the two-dimensional (2D) triangular lattice antiferromagnets HCrO(2), LiCrO(2), and NaCrO(2) is investigated by electron spin resonance. In these oxides, on approaching the Neacuteel temperature T(N) from above, the divergence of the temperature dependent linewidth is well described in terms of a Berezinskii-Kosterlitz-Thouless scenario due to magnetic vortex-antivortex pairing. A refined analysis suggests analogies to the melting scenario of a 2D triangular lattice described by Nelson, Halperin, and Young.