Weakly ferromagnetic metallic state in heavily doped Ba1-xKxMn2As2

Heavily doped Ba1-xKxMn2As2 (x = 0.19 and 0.26) single crystals were successfully grown and investigated by the measurements of resistivity and anisotropic magnetization. In contrast to the antiferromagnetic insulating ground state of the undoped BaMn2As2, the K-doped crystals show metallic conduction with weak ferromagnetism below similar to 50 K and Curie-Weiss-like in-plane magnetic susceptibility above similar to 50 K. Under high pressures up to 6 G Pa, the low-temperature metallicity changes into a state characterized by a Kondo-like resistivity minimum. Electronic structure calculations for x = 0.25 using a 2 x 2 x 1 supercell reproduce the hole-doped metallic state. The density of states at Fermi energy has significant As-4p components, indicating that the 4p holes are mainly responsible for the metallic conduction. Our results suggest that the interplay between the itinerant 4p holes and the local 3d moments is mostly responsible for the novel metallic state.