Abstract

We propose a symmetry-resolved optical probe of intrinsic loop-current chirality in moiré materials, with twisted bilayer graphene as a representative realization. Interlayer interference generates chiral electronic circulation on triangular plaquettes, giving rise to an intrinsic geometric chirality that enters the second-order response through a C₃-selected angular harmonic of the Berry curvature and can be isolated by the orbital-angular-momentum difference Δℓ of interfering optical vortex beams. When moiré C₃ symmetry is preserved, the intrinsic contribution appears in the Δℓ = 3 channel of the helicity-dependent dc photocurrent, whereas C₃-breaking perturbations activate additional channels. These results establish angular-momentum-resolved nonlinear optics as a route to probing geometric chirality in moiré and other symmetry-engineered quantum materials.

Abstract

We propose a symmetry-resolved optical probe of intrinsic loop-current chirality in moiré materials, with twisted bilayer graphene as a representative realization. Interlayer interference generates chiral electronic circulation on triangular plaquettes, giving rise to an intrinsic geometric chirality that enters the second-order response through a C₃-selected angular harmonic of the Berry curvature and can be isolated by the orbital-angular-momentum difference Δℓ of interfering optical vortex beams. When moiré C₃ symmetry is preserved, the intrinsic contribution appears in the Δℓ = 3 channel of the helicity-dependent dc photocurrent, whereas C₃-breaking perturbations activate additional channels. These results establish angular-momentum-resolved nonlinear optics as a route to probing geometric chirality in moiré and other symmetry-engineered quantum materials.

Abstract

We propose a symmetry-resolved optical probe of intrinsic loop-current chirality in moiré materials, with twisted bilayer graphene as a representative realization. Interlayer interference generates chiral electronic circulation on triangular plaquettes, giving rise to an intrinsic geometric chirality that enters the second-order response through a C₃-selected angular harmonic of the Berry curvature and can be isolated by the orbital-angular-momentum difference Δℓ of interfering optical vortex beams. When moiré C₃ symmetry is preserved, the intrinsic contribution appears in the Δℓ = 3 channel of the helicity-dependent dc photocurrent, whereas C₃-breaking perturbations activate additional channels. These results establish angular-momentum-resolved nonlinear optics as a route to probing geometric chirality in moiré and other symmetry-engineered quantum materials.

Abstract

We propose a symmetry-resolved optical probe of intrinsic loop-current chirality in moiré materials, with twisted bilayer graphene as a representative realization. Interlayer interference generates chiral electronic circulation on triangular plaquettes, giving rise to an intrinsic geometric chirality that enters the second-order response through a C₃-selected angular harmonic of the Berry curvature and can be isolated by the orbital-angular-momentum difference Δℓ of interfering optical vortex beams. When moiré C₃ symmetry is preserved, the intrinsic contribution appears in the Δℓ = 3 channel of the helicity-dependent dc photocurrent, whereas C₃-breaking perturbations activate additional channels. These results establish angular-momentum-resolved nonlinear optics as a route to probing geometric chirality in moiré and other symmetry-engineered quantum materials.