Negative longitudinal magnetoresistance in Dirac and Weyl metals

By A. Burkov. 2015

149 citations recorded by the source corpus.

It has recently been found that Dirac and Weyl metals are characterized by an unusual weak-field longitudinal magnetoresistance: large, negative, and quadratic in the magnetic field. This has been shown to arise from the chiral anomaly, i.e., nonconservation of the chiral charge in the presence of external electric and magnetic fields, oriented collinearly. In this paper we report on a theory of this effect in both Dirac and Weyl metals. We demonstrate that this phenomenon contains two important ingredients. One is the magnetic-field-induced coupling between the chiral and the total (or vector, in relativistic field theory terminology) charge densities. This arises from the Berry curvature and is present in principle whenever the Berry curvature is nonzero, i.e., is nonspecific to Dirac and Weyl metals. This coupling, however, leads to a large negative quadratic magnetoresistance only when the second ingredient is present, namely when the chiral charge density is a nearly conserved quantity with a long relaxation time. This property is specific to Dirac and Weyl metals and is realized only when the Fermi energy is close to Dirac or Weyl nodes, expressing an important low-energy property of these materials, emergent chiral symmetry.

Subfields: Atomic and Molecular Physics, and Optics, Condensed Matter Physics, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/83a64a61ba667c8beaa90a00536b6f681720fa02

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In Atomic and Molecular Physics, and Optics

In Condensed Matter Physics

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Citations in the corpus

Weyl and Dirac semimetals in three-dimensional solids (2017, methodology): “Instead if the relaxation is to be small between states of opposite chirality at the same k0 in a DSM (Burkov, 2015b), this is presumably 25 because scattering is suppressed by the same symmetries that protect the Dirac node itself.”
Inhomogeneous Weyl and Dirac Semimetals: Transport in Axial Magnetic Fields and Fermi Arc Surface States from Pseudo-Landau Levels (2016, background): “One particularly striking feature that has been confirmed in several experiments [39–66,85] is the appearance of a nonsaturating negative magnetoresistance [86,87].”