Abstract
Topological materials possessing non-trivial Bloch band Berry curvature textures can often lead to a wealth of novel transport and optical properties. One example arises from the combined action of electron interactions and Berry curvature, revealing a new class of collective modes — Berry plasmons. Berry plasmons manifest as chiral propagating plasmonic modes, which are confined to system boundaries, and appear even in the absence of a magnetic field. They exhibit a rich phenomenology including split energy dispersions for oppositely directed plasmon modes, with splitting that depends directly on interaction strength. Berry plasmons arise generically in anomalous Hall metals, and provide a window into the role of interactions in topological matter.
A second example are collective modes of Fermi-arc carriers in time reversal broken Weyl semimetals. These chiral fermi arc plasmons possess open dispersions, featuring hyperbolic constant frequency contours and group velocity vectors directed along a few specific collimated directions. As a result, a large range of surface plasmon wave vectors can be supported at a given frequency. Both Berry plasmons and Fermi-arc plasmons can be probed via nanophotonic methods, and are parts of an increasingly rich new opto-electronic tool box in topological matter.
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