Abstract
The current density j^{B} induced in a clean metal by a slowly-varying magnetic field B is formulated as the low-frequency limit of natural optical activity, or natural gyrotropy. Working with a multiband Pauli Hamiltonian, we obtain from the Kubo formula a simple expression for α_{ij}^{GME}=j_{i}^{B}/B_{j} in terms of the intrinsic magnetic moment (orbital plus spin) of the Bloch electrons on the Fermi surface. An alternate semiclassical derivation provides an intuitive picture of the effect, and takes into account the influence of scattering processes in dirty metals. This "gyrotropic magnetic effect" is fundamentally different from the chiral magnetic effect driven by the chiral anomaly and governed by the Berry curvature on the Fermi surface, and the two effects are compared for a minimal model of a Weyl semimetal. Like the Berry curvature, the intrinsic magnetic moment should be regarded as a basic ingredient in the Fermi-liquid description of transport in broken-symmetry metals.
Highlights
Introduction.— When a solid is placed in a static magnetic field the nature of the electronic ground state can change, leading to striking transport effects
This “gyrotropic magnetic effect” is fundamentally different from the chiral magnetic effect driven by the chiral anomaly and governed by the Berry curvature on the Fermi surface, and the two effects are compared for a minimal model of a Weyl semimetal
Novel magnetotransport effects have been predicted to occur in 3D topological (Weyl) metals, such as an anomalous longitudinal magnetoresistence [2, 3], and the chiral magnetic effect (CME), where an electric pulse E B induces a transient current j B [4]; both are related to the chiral anomaly that was originally discussed for Weyl fermions in particle physics [5, 6]
Summary
Introduction.— When a solid is placed in a static magnetic field the nature of the electronic ground state can change, leading to striking transport effects. The current density jB induced in a clean metal by a magnetic field B is formulated as the low-frequency limit of natural optical activity, or natural gyrotropy.
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