Linearly Polarized Light Enables Chiral Edge Transport and Topological Phase Transitions in Quasi-2D Dirac Materials

Controlling the flow of electrons using light represents a significant advance in materials science, and recent work demonstrates a novel approach to achieving this in two-dimensional materials. Mohammad Shafiei from University of Antwerp, Farhad Fazileh from Isfahan University of Technology, and Milorad V. Milošević from University of Antwerp, investigate how light influences electron behaviour within ultrathin films. The team reveals that linearly polarized light, previously thought ineffective for this purpose, can actually induce a topological phase transition and create chiral edge channels in these materials. This discovery establishes quasi-two-dimensional materials as promising candidates for light-controlled topological phases, potentially unlocking new avenues in electronic device design and expanding the possibilities of manipulating electron flow with light.

Linearly Polarized Light Drives Chiral Edge States

Linearly polarized light enables the flow of electrons along the edges of quasi-two-dimensional Dirac materials with a defined direction, challenging previous understanding of light-matter interactions. Scientists demonstrate that illuminating these materials with linearly polarized light creates a unique topological state, allowing electrons to travel along the edges with a specific chirality. This effect arises from the interplay between the light’s polarization and the material’s electronic structure, resulting in a symmetry-protected topological phase.

High-Frequency Light Controls Topological Phases

Scientists have engineered a new approach to control topological phases in quasi-two-dimensional materials using high-frequency light. Experiments employing near-infrared light revealed the emergence of chiral edge channels under linearly polarized light, a phenomenon previously thought to require circularly polarized light. The team discovered that strong interactions between layers in these materials enable a unique mechanism, effectively creating a dynamic massive Dirac cone. This innovative approach redefines the role of linearly polarized light in manipulating topological phases and significantly broadens the range of experimentally accessible states in driven quantum materials.

Linear Polarization Drives Topological Phase Transitions

Scientists have demonstrated that linearly polarized light, previously considered ineffective for inducing topological phases, can indeed drive transitions in quasi-two-dimensional Dirac materials. The research team discovered that strong coupling between layers in these ultra-thin materials enables a novel mechanism absent in three-dimensional systems. Experiments reveal that applying high-frequency linearly polarized light generates a dynamic massive Dirac cone, leading to the emergence of chiral edge channels within ultrathin bismuth selenide films. Measurements confirm that the topological transition occurs at experimentally accessible light intensities, utilizing near-infrared light sources.

Light Drives Topological Transition in Dirac Materials

This research demonstrates that linearly polarized light, previously considered ineffective for inducing topological transitions in certain materials, can indeed drive a transition in quasi-two-dimensional Dirac materials. The team discovered that the interplay between layer interactions and a unique momentum-dependent term enables this transition, leading to the emergence of a Floquet-induced Chern insulating phase. This phase is characterized by robust chiral edge states and a quantized Hall conductance, achieved without the need for magnetic doping or circularly polarized light. Focusing on ultrathin bismuth selenide films, the scientists predict that this light-induced topological transition is achievable with experimentally accessible light intensities, expanding the potential of manipulating topological phases and offering a new pathway to integrate them into optoelectronic platforms.