Thermoelectric and viscous contributions to the hydrodynamic ratchet effect

Abstract

We study thermoelectric and viscous contributions to the ratchet effect, i.e. radiation-induced generation of the direct electric current, $J_{\mathrm{rat}},$ in asymmetric dual-grating gate structure without inversion center. Previously [E.Mönch et al, Phys. Rev. B {\bf 105}, 045404 (2022)], it was demonstrated that frequency dependence of the $J_{\mathrm{rat}}$ is essentially different within hydrodynamic (HD) and drift-diffusion (DD) regimes of the electron transport: $J_{\mathrm{rat}}^{\mathrm{HD}}\propto 1/{\omega }^6$ and $J_{\mathrm{rat}}^{\mathrm{DD}}\propto 1/{\omega }^2$ for $\omega \to \infty .$ Here we analyze previously neglected thermoelectric contribution and find that it yields high-frequency asymptotic $1/{\omega }^2$ even in the HD regime and can change sign of the response. Account of the finite viscosity of the electron liquid yields contribution which scales at high frequency as $1/{\omega }^4.$ We also find plasmonic resonances in the $J_{\mathrm{rat}},$ and demonstrate that asymmetry of the structure allows for excitation of the so-called directional travelling plasmons.

13 pages, 5 figures. arXiv admin note: text overlap with arXiv:2111.09169