Observation of Terahertz Spin Hall Conductivity Spectrum in GaAs with Optical Spin Injection

Abstract

We report the first observation of the spin Hall conductivity spectrum in GaAs at room temperature. Our terahertz polarimetry with a precision of several μrads resolves the Faraday rotation of terahertz pulses arising from the inverse spin Hall effect of optically injected spin-polarized electrons. The obtained spin Hall conductivity spectrum exhibits an excellent quantitative agreement with theory, demonstrating a crossover in the dominant origin from impurity scattering in the dc regime to the intrinsic Berry-curvature mechanism in the terahertz regime. Our spectroscopic technique opens a new pathway to analyze anomalous transports related to spin, valley, or orbital degrees of freedom.Received 16 May 2023Accepted 21 November 2023DOI:https://doi.org/10.1103/PhysRevLett.132.016301© 2024 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasInverse spin Hall effectSpin Hall effectPhysical SystemsIII-V semiconductorsTechniquesTerahertz spectroscopyCondensed Matter, Materials & Applied Physics