Topological and Transport Properties of Dirac Fermions in Antiferromagnetic Metallic Phase of Iron-Based Superconductors

TL;DR

This paper explores the topological and transport characteristics of Dirac fermions in the antiferromagnetic metallic phase of iron-based superconductors, revealing unique chiral Dirac cones and their impact on transport phenomena.

Contribution

It derives an effective Hamiltonian showing two same-chirality Dirac cones and links Dirac fermions to observable transport property differences in iron-based superconductors.

Findings

Existence of two same-chirality Dirac cones in the band structure.

Presence of a quadratic Fermi surface compensating the Dirac cones.

Correlation between Dirac fermions and sign-change temperatures in Hall coefficient and thermopower.

Abstract

We investigate Dirac fermions in the antifferomagnetic metallic state of iron-based superconduc- tors. Deriving an effective Hamiltonian for Dirac fermions, we reveal that there exist two Dirac cones carrying the same chirality, contrary to graphene, compensated by a Fermi surface with a quadratic energy dispersion as a consequence of a non-trivial topological property inherent in the band structure. We also find that the presence of the Dirac fermions gives the difference of sign- change temperatures between the Hall coefficient and the thermopower. This is consistent with available experimental data.