Emergence of threefold symmetric helical photocurrents in epitaxial low twinned Bi₂Se₃.

ABSTRACT: We present evidence of a strong circular photon drag effect (PDE) in topological insulators (TIs) through the observation of helicity-dependent topological photocurrents with threefold rotational symmetry using THz spectroscopy in epitaxially-grown Bi₂Se₃ with reduced crystallographic twinning. We establish how twinned domains introduce competing nonlinear optical (NLO) responses inherent to the crystal structure that obscure geometry-sensitive optical processes through the introduction of a spurious mirror symmetry. Minimizing the twinning defect reveals strong NLO response currents whose magnitude and direction depend on the alignment of the excitation to the crystal axes and follow the threefold rotational symmetry of the crystal. Notably, photocurrents arising fro

SUBMITTER: Connelly BC 

PROVIDER: S-EPMC10835140 | biostudies-literature | 2024 Jan

REPOSITORIES: biostudies-literature