ORDER FROM DISORDER IN A KAGOME ANTIFERROMAGNET

It will be discussed to what extent the large S approach to an antifer romagnet on a kagome lattice can explain the data of magnetothermal an d neutron scattering experiments on a stacked kagome antiferromagnet S r-Cr-Ga-O. In particular, it will be shown that quantum fluctuations l ift the classical degeneracy related to a large amount of frustration in a kagome lattice and give rise to a finite velocity of spin-wave ex citations which is by a factor S-1/3 smaller than for a conventional a ntiferromagnet.