Tunable chiral symmetry breaking in symmetric Weyl materials

TL;DR

This paper explores how external magnetic fields can induce tunable chiral symmetry breaking in symmetric Weyl semimetals, enabling control over fermion chirality imbalance and related effects.

Contribution

It derives conditions for chiral symmetry breaking in symmetric Weyl materials and demonstrates tunability via magnetic field orientation and strength.

Findings

Magnetic fields along specific directions break chiral symmetry in certain materials.

Chiral imbalance can be tuned by changing magnetic field parameters.

Imbalance between type I Weyl cones of different chiralities can occur.

Abstract

Asymmetric Weyl semimetals, which possess an inherently chiral structure, have different energies and dispersion relations for left- and right-handed fermions. They exhibit certain effects not found in symmetric Weyl semimetals, such as the quantized circular photogalvanic effect and the helical magnetic effect. In this work, we derive the conditions required for breaking chiral symmetry by applying an external field in symmetric Weyl semimetals. We explicitly demonstrate that in certain materials with the $T_d$ point group, magnetic fields along low symmetry directions break the symmetry between left- and right-handed fermions; the symmetry breaking can be tuned by changing the direction and magnitude of the magnetic field. In some cases, we find an imbalance between the number of type I left- and right-handed Weyl cones (which is compensated by the number of type II cones of each chirality.)