The specific heat and critical behaviour of VBr2, a Heisenberg antiferromagnet with chiral symmetry

We present high-resolution measurements of the specific heat, C, of the Heisenberg antiferromagnet VBr 2 with layered-triangular lattice in the temperature range between 1.5 and 35 K and in fields up to 6 T. The critical exponent alpha extracted from C has been obtained as alpha =0.30+or-0.05. This value is fully consistent with the theoretically expected exponent of alpha =0.24+or-0.08 for three-dimensional Heisenberg systems with chiral symmetry.