A Photoinduced Floquet Mixed-Weyl Semimetallic Phase in a Carbon Allotrope

TL;DR

This paper demonstrates through first-principles and Floquet theory that a carbon allotrope can undergo a light-induced topological phase transition from a nodal-line semimetal to a Weyl semimetal with tunable Weyl points, revealing novel topological features.

Contribution

It introduces a new photoinduced topological phase transition in a carbon allotrope, showing the emergence of unconventional Weyl pairs with distinct types of Weyl points.

Findings

Light induces a transition from nodal-line to Weyl semimetal in bct-C$_{16}$.

Weyl points can be tuned from type-I to type-II with increasing light intensity.

Floquet Fermi arcs reveal the topological nature of the photoinduced Weyl points.

Abstract

The interplay between light and matter attracts tremendous interest for exploring novel topological quantum states and their phase transitions. Here we show by first-principles calculations and the Floquet theorem that a carbon allotrope bct-C$_{16}$, a typical nodal-line semimetal, exhibits exotic photoinduced Floquet mixed-Weyl semimetallic features. Under the irradiation of a linearly polarized light, bct-C$_{16}$ undergos a topological phase transition from a Driac nodal-line semimetal to a Weyl semimetal with two pairs of tunable Weyl points. With increasing the light intensity, left-handed Weyl points evolve from type-I into type-II while right-handed ones are always preserved to be type-I, giving rise to photo-dressed unconventional Weyl pairs composed of distinct types of Weyl points. Importantly, a special Weyl pair formed by type-I and type-III Weyl points is present at the boundary between type-I and type-II states. The Floquet Fermi arcs connecting the projections of two different types of Weyl points are clearly visible, further revealing their unique topological features. Our work not only realizes promising unconventional Weyl pairs but also paves a reliable avenue for investigating light-induced topological phase transitions.