Transport and magnetic properties in polycrystalline Ba(Mn1−xCrx)2As2 and Ba0.8K0.2(Mn1−xCrx)2As2

Here we report the structure, electrical and magnetic properties of polycrystalline Ba(Mn1−xCrx)2As2 (x=0.0-0.1) and Ba0.8K0.2(Mn1−xCrx)2As2 (x=0.0-0.4). Upon the substitution of Cr for Mn in BaMn2As2 semiconductor, it is found that the resistivity can be substantially decreased by five orders in magnitude without changing the structural symmetry. The XPS and Hall measurements demonstrate that the valence of doped Cr is +3 instead of expected Cr2＋, which can effectively introduce electron carriers. Meanwhile, a magnetic transition shows up at ∼40 K with small saturated moment of Msat=0.02 μB/Mn(Cr) and a low coercive field of Hc=135 Oe. The transition may originate from the change in spin re-orientation from ideal AFM to canted AFM state. For p-type AFM metal Ba0.8K0.2Mn2As2, doping Cr3＋ equivalently provides electrons to compensate the holes, leading to a metal–semiconductor transition and a similar canted AFM state. Our results demonstrate that majority carriers, resistivity and magnetism in BaMn2As2 can be controlled through relatively low levels of Cr3＋ doping.