Magnetotransport of multiple-band nearly-antiferromagnetic metals due to "hot-spot" scattering

TL;DR

This paper analyzes how antiferromagnetic spin fluctuations influence magnetotransport in multi-band metals, revealing anomalous behaviors such as linear and quadratic magnetic field dependencies due to hot-spot scattering.

Contribution

It provides an analytical solution to the Boltzmann transport equation considering hot-spot scattering, improving accuracy over relaxation-time approximation and explaining anomalous magnetotransport phenomena.

Findings

Longitudinal conductivity shows linear magnetic field dependence.

Hall conductivity exhibits quadratic magnetic field dependence.

Hot-spot scattering causes anomalous magnetotransport behavior.

Abstract

Multiple-band electronic structure and proximity to antiferromagnetic (AF) instability are the key properties of iron-based superconductors. We explore the influence of scattering by the AF spin fluctuations on transport of multiple-band metals above the magnetic transition. A salient feature of scattering on the AF fluctuations is that it is strongly enhanced at the Fermi surface locations where the nesting is perfect ("hot spots" or "hot lines"). We review derivation of the collision integral for the Boltzmann equation due to AF-fluctuations scattering. In the paramagnetic state, the enhanced scattering rate near the hot lines leads to anomalous behavior of electronic transport in magnetic field. We explore this behavior by analytically solving Boltzmann transport equation with approximate transition rates. This approach accounts for return scattering events and is more accurate than the relaxation-time approximation. The magnetic-field dependences are characterized by two very different field scales, the lower scale is set by the hot-spot width and the higher scale is set by the total scattering amplitude. A conventional magnetotransport behavior is limited to magnetic fields below the lower scale. In the wide range in between these two scales the longitudinal conductivity has linear dependence on the magnetic field and the Hall conductivity has quadratic dependence. The linear dependence of the diagonal component reflects growth of the Fermi-surface area affected by hot spots proportional to the magnetic field. We discuss applicability of this theoretical framework for describing of anomalous magnetotransport properties in different iron pnictides and selenides in the paramagnetic state.