Bertrand REULET

    Département de Physique et Institut Quantique, Université de Sherbrooke, Sherbrooke, Canada
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    Faraday rotation by the Quantum and Classical Hall effects in a 2D electron gas

    The Hall effect in a 2D electron gas (2DEG) leads to a rotation of the polarization plane of a linearly polarized electromagnetic wave impinging on the 2DEG. We show two experiments that provide a quantitative probe of this phenomenon in the microwave domain using a GaAs/AlGaAs semiconductor heterostructure in a waveguide. First, working with a 2DEG of mobility one million, we demonstrate the quantization of the angle of Faraday rotation at high magnetic field, reminiscent of the Quantum Hall effect observed in DC transport [1]. Second, working with a 2DEG of higher mobility in the collisionless limit, where the frequency is larger than the inverse scattering time, we show that the quantization disappears, but that a single pass rotation close to 90 degrees can be achieved with appropriate coupling between the 2DEG and the waveguide [2].

    [1] V. Suresh et al., Phys. Rev. B102, 085302 (2020).
    [2] V. Suresh et al., arXiv2509.05819. To appear in Nat. Comm.