Bloch-band quantum geometry and new collective modes

The internal structure of quasiparticles (such as spin or valley quantum numbers), while conventionally obscured from view, can dramatically alter their behavior when they couple with kinematic degrees of freedom. Featuring prominently in topological materials, this [UTF-8?]“spin-orbit”-type coupling can lead to unusual classes of behavior such as topological edge states, as well as quasiparticles that can acquire geometric phases as they propagate skewing their trajectories and enriching their dynamics.

I will discuss how the unusual carrier dynamics in topological materials lead to a new range plasmons, the collective modes of an electron iquid. Examples include anomalous Hall (Berry) plasmons that acquire a hirality even in the absence of an applied magnetic field in anomalous Hall metals, as well as collective oscillations of carriers in topological edge states that exhibit unusual spectral properties (e.g., hyperbolicity, extended lifetimes) owing to their edge-state origin.

If time permits, I will also discuss how plasmon quasiparticles can also possess and emergent internal (hidden) structure. This emergent non-trivial texture arises from the local current density configuration of plasmons and can take on an intricate pattern when a magnetic field is applied, exhibiting a non-trivial winding. As a result, plasmons to pick up non-trivial geometric phases when they scatter and dramatically alters their dynamics yielding new means for directing plasmonic beams, as well as a window into the hidden lives of plasmon oscillations.