Fundamental conservation laws predict ballistic, i.e., dissipationless transport behaviour in one-dimensional quantum magnets. Experimental evidence, however, for such anomalous transport has been lacking ever since. Here we provide experimental evidence for ballistic heat transport in a S=1/2 Heisenberg chain. In particular, we investigate high purity samples of the chain cuprate SrCuO2 and observe a huge magnetic heat conductivity κmag. An extremely large spinon mean free path of more than a micrometer demonstrates that κmag is only limited by extrinsic scattering processes which is a clear signature of ballistic transport in the underlying spin model.
@article{arxiv.0908.1681,
title = {Ballistic heat transport of quantum spin excitations as seen in SrCuO2},
author = {N. Hlubek and P. Ribeiro and R. Saint-Martin and A. Revcolevschi and G. Roth and G. Behr and B. Büchner and C. Hess},
journal= {arXiv preprint arXiv:0908.1681},
year = {2010}
}