Quasi-Topological Electromagnetic Response of Line-node Semimetals

TL;DR

This paper investigates the electromagnetic response of line-node semimetals, revealing an intrinsic 2-form response field linked to their geometric and energetic properties, with implications for novel materials and heterostructures.

Contribution

It introduces a layered approach to derive an intrinsic 2-form response field in line-node semimetals, connecting it to their polarization and magnetization.

Findings

Emergence of an intrinsic 2-form response field in line-node semimetals

Relation of the 2-form to charge polarization and orbital magnetization

Implications for materials with line-node Fermi surfaces

Abstract

Topological semimetals are gapless states of matter which have robust surface states and interesting electromagnetic responses. In this paper, we consider the electromagnetic response of gapless phases in $3+1$-dimensions with line nodes. We show through a layering approach that an intrinsic $2$-form ${\cal{B}}_{\mu\nu}$ emerges in the effective response field theory that is determined by the geometry and energy-embedding of the nodal lines. This 2-form is shown to be simply related to the charge polarization and orbital magnetization of the sample. We conclude by discussing the relevance for recently proposed materials and heterostructures with line-node fermi-surfaces.