Crystal distortion and magnetic structure of γ‐MnGe alloys

We have made magnetic susceptibility measurements, the X-ray and neutron diffraction experiments for γ-MnGe alloys. The 12.3 at% alloy at 10 K shows an orthorhombic structure with a = 3.774, b = 3.722 and c = 3.675 Å, and a non-collinear antiferomagnetic structure with μ = 0, μb = 1.33 and μc = 2.10μB/Mn atom. The more Ge rich alloy containing 15 at% Ge shows a tetragonal structure with a = 3.687 and c = 3.775 Å (c/a = 1.024) at 19 K and an antiferromagnetism with the magnetic moment μ is 2.57 μB/Mn atom, and lies in the c plane at 10 K. On the other hand, the Mn rich alloy with containing 9 at% Ge shows a different tetragonal structure with a = 3.742 and c = 3.601 Å (c/a = 0.962) at 19 K and a simple collinear antiferromagnetic structure with μa = μb = 0 and μc = 2.10 μB/Mn atom at 10 K. We have proposed a phase diagram in the γ-MnGe system form 8 to 16 at% Ge. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)