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Magnetotransport phenomena in terahertz and dc driven Dirac fermion systems

Subject Area Theoretical Condensed Matter Physics
Term from 2021 to 2023
Project identifier Deutsche Forschungsgemeinschaft (DFG) - Project number 466114853
 
Final Report Year 2023

Final Report Abstract

The cyclotron resonance (CR) is one of the most fundamental and well-studied phenomena in magnetooptics. Our studies reveal that the near-field enhancement of electromagnetic field in the terahertz range of frequencies can induce a giant photoresistance signals of two-dimensional electron systems (2DES) at overtones of the CR, driven by the non-local dynamic response of electrons to the short-wavelength components of the near field. The resulting non-local Bernstein plasmonic modes feature spectral gaps and vanishing group velocity leading to giant strongly asymmetric features in the transport photoresponse at the overtones of the CR. While the nearfield enhancement can be routinely induced by the nearby metallic pieces of sufficiently small size, our further studies show that even uniform and large-area high-quality 2DES may exhibit anomalous properties under the plane-wave continuous THz illumination which are not captured by the standard local models of the light-matter interaction. Specifically, we have found that the resonant electron heating induced by the Drude CR absorption tends to become completely insensitive to the sense of circular polarization of the incoming THz wave at low temperatures. Future studies should establish whether these helicity anomalies are induced by a strong nonuniformity of the scattering potential and associated electron currents in 2DES, creating a helicity-insensitive near field, or rather by external factors, such as near-field THz diffraction at local charged dipoles in the dielectric matrix surrounding 2DES.

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