Appearance of ferromagnetism in Heusler alloy Ru₂Mn_1-xV_xGe

The crystallographic and magnetic properties of the quaternary Heusler alloys Ru₂Mn_1−xV_xGe were investigated. Although the end members, Ru₂MnGe (x = 0) and Ru₂VGe (x = 1), are antiferromagnetic and paramagnetic, ferromagnetism with Curie temperature over 200 K appeared at about x = 0.3. The saturation magnetization had a maximum (1.6μ_B/f.u.) at x = 0.5. The ferromagnetism was explained by a model which assumes a preferential site occupation of V atoms and a collapsing of the next nearest-neighbor antiferromagnetic Mn-Mn interactions by V.