Novel weak-ferromagnetic metallic state in heavily doped Ba$_{1-x}$K$_{x}$Mn$_{2}$As$_{2}$

TL;DR

This study reports the discovery of a weak ferromagnetic metallic state in heavily K-doped BaMn2As2, characterized by resistivity, magnetic susceptibility measurements, and electronic structure calculations, revealing a novel interplay between holes and local moments.

Contribution

It introduces a new metallic state in heavily doped BaMn2As2 with weak ferromagnetism, supported by experimental and theoretical evidence, expanding understanding of doped magnetic semiconductors.

Findings

Heavily doped samples show metallic conduction and weak ferromagnetism.

High pressure induces a Kondo-like resistivity minimum.

Density of states indicates As 4p holes dominate conduction.

Abstract

Heavily doped Ba$_{1-x}$K$_{x}$Mn$_{2}$As$_{2}$ ($x$=0.19 and 0.26) single crystals were successfully grown, and investigated by the measurements of resistivity and anisotropic magnetic susceptibility. In contrast to the antiferromagnetic insulating ground state of the undoped BaMn$_{2}$As$_{2}$, the K-doped crystals show metallic conduction with weak ferromagnetism below $\sim$50 K and Curie-Weiss-like in-plane magnetic susceptibility above $\sim$50 K. Under high pressures up to 6 GPa, the low-temperature metallicity changes into a state characterized by a Kondo-like resistivity minimum without any signature of superconductivity above 2.5 K. Electronic structure calculations for $x$=0.25 using $2\times2\times1$ supercell reproduce the hole-doped metallic state. The density of states at Fermi energy have significant As 4$p$ components, suggesting that the 4$p$ holes are mainly responsible for the metallic conduction. Our results suggest that the interplay between itinerant 4$p$ holes and local 3$d$ moments is mostly responsible for the novel metallic state.