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We report the observation of the terahertz-induced ratchet effect in graphene-based two-dimensional (2D) metamaterials. The metamaterial consists of a graphite gate patterned with an array of triangular antidots placed under a graphene monolayer. We show that the ratchet current appears due to the noncentrosymmetry of the periodic structure unit cell. The ratchet current is generated owing to the combined action of a spatially periodic in-plane electrostatic potential and a periodically modulated radiation electric field caused by near-field diffraction. The magnitude and direction of the ratchet current are shown to be controlled by voltages applied to both back and patterned gates, which change the lateral asymmetry, carrier type, and density. The phenomenological and microscopic theories of ratchet effects in graphene-based 2D metamaterials are developed. The experimental data are discussed in the light of the theory based on the solution of the Boltzmann kinetic equation and the calculated electrostatic potential profile. The theory describes well all the experimental results and shows that the observed ratchet current consists of the Seebeck thermoratchet contribution as well as the linear ratchet one, which is sensitive to the orientation of the radiation electric field vector with respect to the triangles.

Rights:

• http://arxiv.org/licenses/nonexclusive-distrib/1.0/
  

Keyword: Ratchet effect, Graphene 2D metamaterials, Terahertz-induced

Date published: 2024-06-21

Publisher: American Physical Society (APS)

Journal:

• Physical Review B (ISSN: 1550235X) vol. 109 issue. 23

Funding:

• Deutsche Forschungsgemeinschaft 448955585 (GA501/18)
• Deutsche Forschungsgemeinschaft 314695032 – SFB 1277
• Deutsche Forschungsgemeinschaft 426094608 (ER 612/2-1)
• European Commission 101053716
• National Science and Technology Council NSTC 112-2112-M-006-019-MY3
• Japan Society for the Promotion of Science 20H00354
• Japan Society for the Promotion of Science 23H02052
• Ministry of Education, Culture, Sports, Science and Technology

Manuscript type: Author's version (Accepted manuscript)

MDR DOI:

First published URL: https://doi.org/10.1103/physrevb.109.235428

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Updated at: 2025-08-07 08:30:20 +0900

Published on MDR: 2025-08-07 08:17:48 +0900