Plasmonic quantum nonlinear Hall effect in noncentrosymmetric 2D materials

TL;DR

This paper explores how plasmonic resonances in 2D noncentrosymmetric materials can significantly enhance the quantum nonlinear Hall effect, leading to broad-spectrum, highly sensitive terahertz photodetectors.

Contribution

It demonstrates the enhancement of the quantum nonlinear Hall effect via plasmonic resonances and introduces a universal relation between photocurrent and optical absorption in 2D materials.

Findings

Quantum nonlinear Hall effect is greatly enhanced by plasmonic resonances.

High-harmonic plasmons exhibit broad peaks under off-resonant conditions.

A universal relation between photocurrent and optical absorption is established.

Abstract

We investigate an interplay between quantum geometrical effects and surface plasmons through surface plasmonic structures, based on an electron hydrodynamic theory. First we demonstrate that the quantum nonlinear Hall effect can be dramatically enhanced over a very broad range of frequency by utilizing plasmonic resonances and near-field effects of grating gates. Under the resonant condition, the enhancement becomes several orders of magnitude larger than the case without the nanostructures, while the peaks of high-harmonic plasmons expand broadly and emerge under the off-resonant condition, leading to a remarkably broad spectrum. Furthermore, we clarify a universal relation between the photocurrent induced by the Berry curvature dipole and the optical absorption, which is essential for computational material design of long-wavelength photodetectors. Next we discuss a novel mechanism of geometrical photocurrent, which originates from an anomalous force induced by oscillating magnetic fields and is described by the dipole moment of orbital magnetic moments of Bloch electrons in the momentum space. Our theory is relevant to 2D quantum materials such as layered WTe${}_2$ and twisted bilayer graphene, thereby providing a promising route toward a novel type of highly sensitive, broadband terahertz photodetectors.