Ba1-xKxMn2As2: An Antiferromagnetic Local-Moment Metal

The compound BaMn2As2 with the tetragonal ThCr2Si2 structure is a local-moment antiferromagnetic insulator with a Neel temperature T-N = 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 T-N and large mu. Ba1-xKxMn2As2 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 Ba1-xKxMn2As2 class of compounds also forms a bridge between the layered iron pnictides and cuprates and may be useful to test theories of high T-c superconductivity.