Delocalized lowfrequency magnetoplasmon in a twodimensional electron fluid with cylindrical symmetry
Abstract
The properties of a twodimensional (2D) electron system can be drastically altered by a magnetic field applied perpendicular to the 2D plane. In particular, the frequency of its bulk collective excitations becomes gapped at the cyclotron frequency, while the lowfrequency localized excitations, the edge magnetoplasmon (EMP), appear near the system's edge. A new type of the delocalized lowfrequency excitations, the gradient magnetoplasmon, was recently shown to exist in a 2D electron system with a linear density gradient that breaks the system's cylindrical symmetry [Phys. Rev. B 103, 075420 (2021), 10.1103/PhysRevB.103.075420]. Like EMP, these new excitations are gapless and chiral, and originate from the classical Hall effect. Here we show that a similar magnetoplasmon mode can exist in a system with strongly inhomogeneous radial distribution of the electron density that preserves the cylindrical symmetry. This is experimentally demonstrated in a pristine system of surface electrons on liquid helium and is confirmed by a numerical simulation. This result extends the variety of known collective excitations in a 2D charge system and presents electrons on helium as a promising model system for their study.
 Publication:

Physical Review B
 Pub Date:
 April 2024
 DOI:
 10.1103/PhysRevB.109.165150
 arXiv:
 arXiv:2404.07582
 Bibcode:
 2024PhRvB.109p5150K
 Keywords:

 Condensed Matter  Mesoscale and Nanoscale Physics
 EPrint:
 7 pages, 9 figures