Intrinsic Orbital Origin for the Chirality-Dependent Nonlinear Planar Hall Effect of Topological Nodal Fermions in Chiral Crystals

TL;DR

This paper uncovers an intrinsic orbital mechanism behind the chirality-dependent nonlinear planar Hall effect in topological chiral semimetals, linking band topology, orbital magnetic moments, and observable transport phenomena.

Contribution

It reveals a new orbital origin for the nonlinear Hall effect in chiral topological semimetals, emphasizing the role of topological charge and orbital magnetic moments.

Findings

The nonlinear Hall effect reverses sign with chirality change.

Multifold fermions induce a giant nonlinear Hall conductivity.

The effect is detectable and related to band topology and chirality.

Abstract

Topological semimetals in chiral crystals, which possess both structural handedness and band crossings (or nodes) with topological chiral charge, exhibit many exotic physical properties. Here we demonstrate that the structural and electronic chirality of these systems can endow them with another fascinating phenomenon -- the intrinsic nonlinear planar Hall effect (INPHE), which is prominent around the nodes and reverses sign upon chirality reversal in opposite enantiomers. Taking chiral tellurium as an example, we reveal an intrinsic orbital mechanism, which manifests diverging orbital magnetic moments with hedgehog-like textures around nodes and, therefore, generates a dominant contribution to the INPHE that is proportional to the topological charge. Furthermore, we show that multifold fermions in topological chiral semimetals with B20 structures (e.g., CoSi and PtAl) induce a giant INPHE conductivity reaching the order of $1\sim 10\; \mathrm{A}\cdot\mathrm{V}^{-2}\cdot\mathrm{T}^{-1}$, which is detectable in experiments. Our study not only relates nonlinear transport to band topology and enantiomer recognition but also offers a new way to explore the exotic physical properties associated with unconventional chiral fermions.