Kondo-like mass enhancement of Dirac fermion in iron pnictides Ba(Fe$_{1-x}$Mn$_x$As)$_2$

TL;DR

This paper investigates how magnetic impurities from Mn substitution in Ba(Fe$_{1-x}$Mn$_x$As)$_2$ cause an anomalous enhancement of the Dirac fermion effective mass at low temperatures, suggesting a Kondo-like band renormalization effect.

Contribution

It reveals a Kondo-like mass enhancement of Dirac fermions due to magnetic impurity scattering in iron pnictides, a novel observation in this material class.

Findings

Effective mass of Dirac fermions is anomalously enhanced at low temperatures.

Magnetoresistance and Hall measurements support the mass enhancement.

Kondo-like band renormalization is proposed as the underlying mechanism.

Abstract

The effect of Mn substitution, acting as a magnetic impurity for Fe, on the Dirac cone was investigated in Ba(Fe$_{1-x}$Mn$_x$As)$_2$. Both magnetoresistance and Hall resistivity studies clearly indicate that the cyclotron effective mass ($m^{\ast}$) of the Dirac cone is anomalously enhanced at low temperatures by the impurity, although its evolution as a function of carrier number proceeds in a conventional manner at higher temperatures. Kondo-like band renormalization induced by the magnetic impurity scattering is suggested as an explanation for this, and the anomalous mass enhancement of the Dirac fermions is discussed.