Geometric transport signatures of strained multi-Weyl semimetals

TL;DR

This paper investigates how strain affects higher winding number Weyl semimetals, revealing that strain induces geometric signatures and anisotropic Fermi surfaces rather than pseudo-gauge fields, leading to new transport phenomena.

Contribution

It demonstrates that strain acts as a symmetry-breaking field in multi-Weyl semimetals, producing geometric signatures instead of topological pseudo-gauge fields, and extends chiral kinetic theory to describe these effects.

Findings

Strain splits higher winding number Weyl nodes.

Strain induces nematic order in the Fermi surface.

Transport signatures depend on strain-induced geometric coupling.

Abstract

The minimal coupling of strain to Dirac and Weyl semimetals, and its modeling as a pseudo-gauge field has been extensively studied, resulting in several proposed topological transport signatures. In this work, we study the effects of strain on higher winding number Weyl semimetals and show that strain is not a pseudo-gauge field for any winding number larger than one. We focus on the double-Weyl semimetal as an illustrative example to show that the application of strain splits the higher winding number Weyl nodes and produces an anisotropic Fermi surface. Specifically, the Fermi surface of the double-Weyl semimetal acquires nematic order. By extending chiral kinetic theory for such nematic fields, we determine the effective gauge fields acting on the system and show how strain induces anisotropy and affects the geometry of the semi-classical phase space of the double-Weyl semimetal. Further, the strain-induced deformation of the Weyl nodes results in transport signatures related to the covariant coupling of the strain tensor to the geometric tensor associated with the Weyl nodes giving rise to strain-dependent dissipative corrections to the longitudinal as well as the Hall conductance. Thus, by extension, we show that in multi-Weyl semimetals, strain produces geometric signatures rather than topological signatures. Further, we highlight that the most general way to view strain is as a symmetry-breaking field rather than a pseudo-gauge field.