Floquet engineering of the orbital Hall effect in the presence of intrinsic spin-orbit coupling
Phys. Rev. B 113, 245423 – Published 23 June, 2026
DOI: https://doi.org/10.1103/y8sk-kssp
Abstract
The orbital Hall effect has emerged as a fundamental phenomenon in the burgeoning field of orbitronics, offering a robust paradigm for the generation and manipulation of orbital angular momentum. Particularly, two-dimensional valleytronic materials have emerged as highly promising platforms for investigating this effect. Concurrently, Floquet engineering via periodic optical driving provides a powerful nonequilibrium pathway to dynamically control topological quantum states. In this work, we employ Floquet theory to investigate the band topology and the corresponding evolution of orbital transport in a gapped graphenelike model driven by circularly polarized light, aiming to dynamically tune both the magnitude and sign of the orbital angular momentum. We reveal that the interplay between the optical field and intrinsic spin-orbit coupling (SOC) fundamentally reshapes the topological phase transitions. Specifically, SOC functions as a spin-valley-dependent mass correction that breaks the synchronization of photoinduced band inversions. This desynchronization drives the system into a unique mixed topological phase, where only a single spin band within a specific valley undergoes band inversion. Consequently, the orbital transport exhibits a pronounced spin-valley coupled character: within the same valley, the Berry curvature and orbital magnetic moment for the two spin channels acquire opposite signs, leading to highly tunable, valley-resolved orbital angular momentum transport. By further evaluating the orbital Hall angle, we demonstrate that a giant orbital Hall angle emerges in the vicinity of the insulating gap due to the suppression of longitudinal charge transport. Compared with bulk transition metals, this gap-engineered feature provides a more favorable platform for the study and manipulation of orbital angular momentum transport.
