How massless are Weyl fermions in Weyl semimetals?

Abstract

Circularly polarized light fails to generate currents in inversion-symmetric Weyl semimetals with degenerate Weyl nodes. While each node generates current with the direction depending on its chirality, the two currents in the two degenerate nodes of opposite chirality cancel each other. By extension, it is also generally expected that the currents generated at the same Weyl node by the fields of opposite helicity should also observe mirror symmetry and cancel. Surprisingly, here we find that this is not the case. The origin of this effect lies in the nonlinear energy dispersion, which manifests strongly already very close to the Weyl nodes, where linear dispersion is expected to hold and the Weyl fermions are thus expected to be massless. A scheme based on using a trefoil field composed of a counterrotating fundamental and its second harmonic is proposed to control the induced asymmetry at a chiral node from positive to negative, including zero.

12 pages, 6 figures

References in corpus (9)

• Anomalous Hall Effect in Weyl Metals
• Photocurrents in Weyl semimetals
• Light-Induced Valleytronics in Pristine Graphene
• Experimental observation of anisotropic Adler-Bell-Jackiw anomaly in type-II Weyl semimetal WTe${}_{1.98}$ crystals at the quasi-classical regime
• Photogalvanic effect in Weyl semimetals
• High-Harmonic Generation from Monolayer and Bilayer Graphene
• High-Harmonic Spectroscopy of Coherent Lattice Dynamics in Graphene
• Controlling Valley-Polarisation in Graphene via Tailored Light Pulses
• The Chiral Qubit: quantum computing with chiral anomaly

Cited by in corpus (1)

• Tailoring Photocurrent in Weyl Semimetals via Intense Laser Irradiation