Electrochemical transport in Dirac nodal-line semimetals

¹ Max Planck Institute for the Physics of Complex Systems - Nöthnitzer Str. 38, 01187 Dresden, Germany
² Max Planck Institute for Chemical Physics of Solids - Nöthnitzer Str. 40, 01187 Dresden, Germany
³ Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México - 04510 Ciudad de México, México

^(a) E-mail: alberto.martin@nucleares.unam.mx (corresponding author)

Received: 17 December 2022
Accepted: 14 June 2023

Abstract

Nodal-line semimetals are topological phases where the conduction and the valence bands cross each other along one-dimensional lines in the Brillouin zone, which are symmetry protected by either spatial symmetries or time-reversal symmetry. In particular, nodal lines protected by the combined symmetry exhibits the parity anomaly of 2D Dirac fermions. In this letter, we study the electrochemical transport in Dirac nodal-line semimetals by using the semiclassical Boltzmann equation approach. We derive a general formula for the topological current that includes both the Berry curvature and the orbital magnetic moment. We first evaluate the electrochemical current by introducing a small mass term (which could be induced by inversion-breaking uniaxial strain, pressure, or an external electric field) and apply it to the hexagonal pnictide CaAgP. The electrochemical current vanishes in the zero-mass limit. Introducing a tilting term that does not spoil symmetry that protects the nodal ring, we obtain a finite electrochemical current in the zero-mass limit, which can be regarded as a direct consequence of the parity anomaly. We show that the parity-anomaly–induced electrochemical transport is also present at nonzero temperatures.