Ballistic heat transport of quantum spin excitations as seen in SrCuO2

TL;DR

This study provides experimental evidence of ballistic heat transport in a one-dimensional quantum magnet, SrCuO2, demonstrating dissipationless spin excitation transport consistent with fundamental conservation laws.

Contribution

First direct experimental observation of ballistic heat transport in a S=1/2 Heisenberg chain using high purity SrCuO2 samples.

Findings

Observation of large magnetic heat conductivity (_{mag})

Spinon mean free path exceeds one micrometer

Transport limited by extrinsic scattering, indicating ballistic behavior

Abstract

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 $\kappa_{mag}$. An extremely large spinon mean free path of more than a micrometer demonstrates that $\kappa_{mag}$ is only limited by extrinsic scattering processes which is a clear signature of ballistic transport in the underlying spin model.