We show that bulk free carriers in topologically trivial multi-valley insulators with non-vanishing Berry curvature give rise to low-dissipation edge currents, which are squeezed within a distance of the order of the valley diffusion length from the edge. This happens even in the absence of edge states [topological (gapless) or otherwise], and when the bulk equilibrium carrier concentration is thermally activated across the gap. Physically, the squeezed edge current arises from the spatially inhomogeneous orbital magnetization that develops from valley-density accumulation near the edge. While this current possesses neither topology nor symmetry protection and, as a result, is not immune to dissipation, in clean enough devices it can mimic low-loss ballistic transport.
@article{arxiv.1805.05955,
title = {Low-dissipation edge currents without edge states},
author = {Justin C. W. Song and Giovanni Vignale},
journal= {arXiv preprint arXiv:1805.05955},
year = {2019}
}