Emergence of the minority hole with high mobility on the electrical transport in the Fe-pnictides Ba(Fe$_{1-x}$Mn$_x$As)$_2$

TL;DR

This study reveals that Mn doping in Ba(Fe$_{1-x}$Mn$_x$As)$_2$ induces high-mobility minority holes through a spin density wave transition, contrasting with other doping methods that lead to superconductivity.

Contribution

It demonstrates that Mn doping generates high-mobility minority holes via SDW transition, differing from other hole-doping mechanisms in Fe pnictides.

Findings

Minority holes with high mobility are generated by Mn doping.

The original majority carriers are negligibly affected by Mn doping.

Hole doping mechanism in Mn-doped BaFeAs differs from other superconducting Fe pnictides.

Abstract

In Fe pnictide (Pn) superconducting materials, neither Mn- nor Cr- doping to the Fe site induces superconductivity, even though hole carriers are generated. This is in strong contrast with the superconductivity appearing when holes are introduced by alkali metal substitution on the insulating blocking layers. We investigate in detail the effects of Mn doping on magneto-transport properties in Ba(Fe$_{1-x}$Mn$_x$As)$_2$ for elucidating the intrinsic reason. The negative Hall coefficient for $x$ = 0 estimated in the low magnetic field ($B$) regime gradually increases as $x$ increases, and its sign changes to a positive one at $x$ = 0.020. Hall resistivities as well as simultaneous interpretation using the magnetoconductivity tensor including both longitudinal and transverse transport components clarify that minority holes with high mobility are generated by the Mn doping via spin density wave (SDW) transition at low temperatures, while original majority electrons and holes residing in the parabolic-like Fermi surfaces (FSs) of the semimetallic Ba(FeAs)$_2$ are negligibly affected. Present results indicate that the mechanism of hole doping in Ba(Fe$_{1-x}$Mn$_x$As)$_2$ is greatly different from that of the other superconducting FePns family.