Chirality Driven Ratchet Currents in Two-Dimensional Tellurene with an Asymmetric Grating

TL;DR

This paper demonstrates a room-temperature terahertz ratchet effect in chiral two-dimensional tellurene, where the generated DC current can be controlled by the helicity of incident radiation, with potential applications in THz detection.

Contribution

It introduces the observation of a chirality-driven ratchet current in tellurene and develops a microscopic Boltzmann-based theory to explain the effect.

Findings

DC circular ratchet current is controlled by radiation helicity.

The effect is observable at room temperature across various Fermi levels.

Theoretical modeling aligns with experimental results.

Abstract

The emergence of the terahertz (THz) ratchet effect is a rapidly expanding field of research that utilizes broken spatial symmetry in low-dimensional materials to rectify alternating current (AC) induced by THz fields into direct current (DC). This mechanism is highly promising for next-generation, room-temperature terahertz applications, particularly in high-speed, sensitive detection and imaging. In this work, we explore a ratchet effect generated in two dimensional tellurene, a novel promising semiconductor material consisting of helical atomic chains, creating a structure with inherent chirality. As a key result, the DC circular ratchet current flowing in the chiral axis direction $c$ is determined by the helicity of the radiation and can be reversed by switching the helicity from right to left handed. The circular ratchet effect excited by THz laser radiation is demonstrated for room temperature. The effect is demonstrated at various gate voltages when the Fermi level lies in vicinity of the Weyl point in the conduction band, in the band gap, and in the valence band with almost parabolic energy dispersion. The results are described by the developed microscopic theory based on the Boltzmann kinetic equation approach.