Circular dichroism of emergent chiral stacking orders in quasi-one-dimensional charge density waves

TL;DR

This study reveals how emergent chiral stacking orders in quasi-1D charge density waves exhibit distinct circular dichroism responses, driven by geometrical chirality and symmetry properties, with implications for optical applications.

Contribution

It demonstrates that chiral stacking orders in quasi-1D CDWs induce observable circular dichroism responses, highlighting the role of symmetry in optical activity.

Findings

Left- and right-chiral stacking orders show distinct circular dichroism responses.

Nonchiral stacking order exhibits no circular dichroism.

Chirality-dependent optical phenomena can be observed via scanning tunneling luminescence.

Abstract

Chirality-driven optical properties in charge density waves are of fundamental and practical importance. Here, we investigate the interaction between circularly polarized light and emergent chiral stacking orders in quasi-one-dimensional (quasi-1D) charge-density waves (CDW) with density-functional theory calculations. In our specific system, self-assembled In nanowires on Si(111) surface, spontaneous mirror symmetry breaking leads to symmetrically distinct four degenerate quasi-1D CDW structures, which exhibit geometrical chirality. Such geometrical chirality may naturally induce optically active phenomena even when the quasi-1D CDW structures are stacked perpendicular to the CDW chain direction. Indeed, we find that left- and right-chiral stacking orders show distinct circular dichroism responses while a nonchiral stacking order does no circular dichroism. Such optical responses are attributed to the existence of glide mirror symmetry of the CDW stacking orders. Our findings suggest that the CDW chiral stacking orders can lead to diverse active optical phenomena such as chirality-dependent circular dichroism, which can be observed in scanning tunneling luminescence measurements with circularly polarized light.