Interlayer Charge-density-wave Vector Phase Induced Structural Chirality

Chiral charge density waves (CDWs) have attracted intense interest due to their exotic quantum properties, yet the microscopic origin of structural chirality emerging from correlated charge order remains elusive.  Here, we reveal that the interlayer phases of CDW wave vectors, an overlooked degree of freedom, play a crucial role in driving chiral structural distortions in layered CDW materials.  By explicitly incorporating the hidden interlayer phases in first-principles calculations, we successfully obtained the chiral structure of the CDW phases of AV₃Sb₅ (A= K, Rb, and Cs) and 1T-TiSe₂. The electronic and optical properties of the predicted chiral structures are consistent with experimental measurements of these materials in their CDW phases. We further predict that 1T-NbSe₂ is a promising material candidate for realizing chiral CDW order.  Beyond materials prediction, our theory reveals that the chiral CDW can be manipulated by electron filling. Our study opens new avenues for discovering, designing, and engineering chiral CDW materials.