title: Chiral plasmons without magnetic field.
abstract: Plasmons, the collective oscillations of interacting electrons, possess emergent properties that dramatically alter the optical response of metals. We predict the existence of a new class of plasmons-chiral Berry plasmons (CBPs)-for a wide range of 2D metallic systems including gapped Dirac materials. As we show, in these materials the interplay between Berry curvature and electron-electron interactions yields chiral plasmonic modes at zero magnetic field. The CBP modes are confined to system boundaries, even in the absence of topological edge states, with chirality manifested in split energy dispersions for oppositely directed plasmon waves. We unveil a rich CBP phenomenology and propose setups for realizing them, including in anomalous Hall metals and optically pumped 2D Dirac materials. Realization of CBPs will offer a powerful paradigm for magnetic field-free, subwavelength optical nonreciprocity, in the mid-IR to terahertz range, with tunable splittings as large as tens of THz, as well as sensitive all-optical diagnostics of topological bands.
authors.affiliation: Walter Burke Institute of Theoretical Physics, California Institute of Technology, Pasadena, CA 91125; Institute of Quantum Information and Matter, California Institute of Technology, Pasadena, CA 91125; Department of Physics, California Institute of Technology, Pasadena, CA 91125; justin.song.cw@gmail.com.
authors.forename: Justin C W
authors.initials: JC
authors.lastname: Song
authors.affiliation: Center for Quantum Devices and Niels Bohr International Academy, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark.
authors.forename: Mark S
authors.initials: MS
authors.lastname: Rudner
keywords: Berry curvature; interactions; nonreciprocal response; topological materials