Ba{1-x}KxMn2As2: An Antiferromagnetic Local-Moment Metal

TL;DR

This study shows that partial potassium substitution in BaMn2As2 transforms it from an antiferromagnetic insulator into a metallic compound while maintaining its magnetic structure, offering insights into high-temperature superconductivity mechanisms.

Contribution

It is the first demonstration of a metallic ThCr2Si2-type MAs-based system with local 3d transition metal moments, bridging iron pnictides and cuprates.

Findings

Ba_{1-x}K_xMn2As2 remains antiferromagnetic and structurally similar after doping.

The compound becomes metallic with potassium substitution.

High Neel temperature and large magnetic moments are retained.

Abstract

The compound BaMn2As2 with the tetragonal ThCr2Si2 structure is a local-moment antiferromagnetic insulator with a Neel temperature TN = 625 K and a large ordered moment mu = 3.9 mu_B/Mn. We demonstrate that this compound can be driven metallic by partial substitution of Ba by K, while retaining the same crystal and antiferromagnetic structures together with nearly the same high TN and large mu. Ba_{1-x}K_xMn2As2 is thus the first metallic ThCr2Si2-type MAs-based system containing local 3d transition metal M magnetic moments, with consequences for the ongoing debate about the local moment versus itinerant pictures of the FeAs-based superconductors and parent compounds. The Ba_{1-x}K_xMn2As2 class of compounds also forms a bridge between the layered iron pnictides and cuprates and may be useful to test theories of high Tc superconductivity.