Signature of inverse orbital Hall effect in silicon studied using time-resolved terahertz polarimetry

TL;DR

This study demonstrates the detection of a long-lived anomalous Hall conductivity in silicon induced by circularly polarized light, indicating the presence of the inverse orbital Hall effect at room temperature.

Contribution

It provides experimental evidence of the inverse orbital Hall effect in silicon using time-resolved terahertz polarimetry, a novel approach in orbitronics research.

Findings

The anomalous Hall conductivity in silicon is comparable to that in GaAs.

The effect depends on light helicity and is robust against photon energy variations.

Results suggest the emergence of the inverse orbital Hall effect in silicon.

Abstract

We investigated the anomalous Hall conductivity induced in silicon by circularly polarized light at room temperature using near-infrared (NIR) pump-terahertz (THz) probe spectroscopy. The time-resolved detection scheme eliminates the large nonlinear current generated by the field-induced circular photogalvanic effect, allowing exclusive observation of a long-lived anomalous Hall conductivity of photocarriers that depends on the helicity of NIR light. The magnitude of this conductivity is comparable to that of GaAs despite silicon's much weaker spin-orbit coupling, and its robustness against NIR photon energy rules out a spin-polarization-based origin, which occurs only in the vicinity of the bandgap. These results suggest the emergence of the inverse orbital Hall effect, paving the way for silicon-based orbitronics.