Vortical effects in chiral band structures

TL;DR

This paper develops a theoretical framework to understand vortical effects in chiral band structures, revealing a new gyrotropic vortical effect governed by Berry curvature and addressing controversies in condensed matter realizations.

Contribution

It introduces a Kubo response theory for electrons in chiral band structures under rotation, discovering the gyrotropic vortical effect and clarifying the chiral vortical effect in condensed matter.

Findings

Recovered the chiral vortical effect in the static limit.

Discovered the gyrotropic vortical effect governed by Berry curvature.

Connected vortical effects to device geometries for potential applications.

Abstract

The chiral vortical effect is a chiral anomaly induced transport phenomenon characterized by an axial current in a uniformly rotating chiral fluid. It is well-understood for Weyl fermions in high energy physics, but its realization in condensed matter band structures, including those of Weyl semimetals, has been controversial. In this work, we develop the Kubo response theory for electrons in a general band structure subject to space- and time-dependent rotation or vorticity relative to the background lattice. We recover the chiral vortical effect in the static limit; in the transport or uniform limit, we discover a new effect that we dub the gyrotropic vortical effect. The latter is governed by Berry curvature of the occupied bands while the former contains an additional contribution from the magnetic moment of electrons on the Fermi surface. The two vortical effects can be understood as analogs of the well-known chiral and gyrotropic magnetic effects in chiral band structures. We address recent controversies in the field and conclude by describing device geometries that exploit Ohmic or Seebeck transport to drive the vortical effects.