Magnetic properties of ββ-MnCoZn alloys

We have found that the ββ-Mn phase in the ternary Mn–Co–Zn alloy system is stable in a very wide composition range, and conducted magnetization measurements, and X-ray and neutron diffraction experiments. We confirmed that the ββ-CoZn and the ββ-Mn24Co36Zn40Mn24Co36Zn40 alloys show a typical ferromagnetism with the Curie temperatures being 460 and 201 K, respectively. It is determined by Rietveld analysis for neutron data that the 8c site is entirely occupied by Co atoms, the 12d site by Zn and the remaining Co atoms, and the magnetic moment μ=1.35μB/Co atom for the former alloy, and the 8c site is entirely occupied by Co and Mn atoms, the 12d site by Zn and the remaining Mn atoms, and the average magnetic moment μ=0.76μB/(Mn or Co) atom for the latter alloy. The more Mn rich ββ-Mn42Co28Zn30Mn42Co28Zn30 alloy shows a micto-magnetic behavior, and has no long range magnetic order.