Moiré Chiral Metamaterials

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Plasmonic chiral metamaterials are promising for applications in chiral sensors and photonic devices due to their strong optical chirality and light–matter interactions at the subwavelength scale. However, most of current plasmonic chiral metamaterials rely on local structural chirality or site‐specific symmetry breaking, which has limited their optical activity, tunability, and scalable fabrication for practical applications. Here, this paper reports a new type of chiral metamaterials consisted of two layers of identical achiral Au nanohole arrays stacked into moiré patterns. The chiroptical responses of the moiré chiral metamaterials can be precisely tuned by the in‐plane rotation between the two layers of nanohole arrays. Furthermore, the moiré chiral metamaterials are applied to achieve label‐free enantiodiscrimination of biomolecules and drug molecules at the picogram level. With their ultrathin thickness (≈70 nm, which is only ≈1/10 of the operation wavelength), strong chirality, and high tunability, the moiré chiral metamaterials will advance a variety of photonic and optoelectronic applications.