Band nonlinearity-enabled manipulation of Dirac nodes, Weyl cones, and valleytronics with intense linearly polarized light

TL;DR

This paper demonstrates how intense linearly polarized light can manipulate Dirac nodes, Weyl cones, and valley properties in topological and valleytronic materials by exploiting band nonlinearities, with potential for tailored electronic structures.

Contribution

It reveals a universal mechanism where band nonlinearities enable control over Dirac and Weyl features using polarized light, validated by ab-initio calculations.

Findings

Dirac nodes can be moved by rotating laser polarization.

Valley minima positions can be tuned in hexagonal materials.

Weyl cones can be split and shifted in Weyl semimetals.

Abstract

We study low-frequency linearly-polarized laser-dressing in materials with valley (graphene and hexagonal-Boron-Nitride), and topological (Dirac- and Weyl-semimetals), properties. In Dirac-like linearly-dispersing bands, the laser substantially moves the Dirac nodes away from their original position, and the movement direction can be fully controlled by rotating the laser polarization. We prove that this effect originates from band nonlinearities away from the Dirac nodes. We further demonstrate that this physical mechanism is widely applicable, and can move the positions of the valley minima in hexagonal materials to tune valley selectivity, split and move Weyl cones in higher-order Weyl semimetals, and merge Dirac nodes in three-dimensional Dirac semimetals. The model results are validated with ab-initio calculations. Our results directly affect efforts for exploring light-dressed electronic-structure, suggesting that one can benefit from band nonlinearity for tailoring material properties, and highlight the importance of the full band structure in nonlinear optical phenomena in solids.