Ratchet effect enhanced by plasmons

TL;DR

This paper investigates how plasmonic resonances significantly amplify the ratchet effect in 2D electron liquids, revealing polarization-dependent behaviors and potential for large transverse currents.

Contribution

It demonstrates the enhancement of the ratchet current near plasmonic resonances and explores polarization effects and non-resonant regimes in high-mobility and dirty systems.

Findings

Ratchet current is dramatically enhanced near plasmonic resonances.

Circular polarization causes the transverse current to change sign with helicity.

In high-mobility structures, the transverse current can exceed the modulation direction current.

Abstract

Ratchet effect -- a {\it dc} current induced by the electromagnetic wave impinging on the spatially modulated two-dimensional (2D) electron liquid -- occurs when the wave amplitude is spatially modulated with the same wave vector as the 2D liquid but is shifted in phase. The analysis within the framework of the hydrodynamic model shows that the ratchet current is dramatically enhanced in the vicinity of the plasmonic resonances and has nontrivial polarization dependence. In particular, for circular polarization, the current component, perpendicular to the modulation direction, changes sign with the inversion of the radiation helicity. Remarkably, in the high-mobility structures, this component might be much larger than the the current component in the modulation direction. We also discuss the non-resonant regime realized in dirty systems, where the plasma resonances are suppressed, and demonstrate that the non-resonant ratchet current is controlled by the Maxwell relaxation in the 2D liquid.