μSR study of the onset of magnetic order in β-Mn–Ru alloys

Abstract Muon spin relaxation has been used to study the transition from spin glass to long-range antiferromagnetism in β-Mn–Ru alloys. Three alloy compositions were studied with 6%, 9% and 19% Ru. The temperature dependence of the muon relaxation is consistent with spin glass order for the two lower concentrations, while for the 19% Ru alloy there are two peaks in the relaxation rate, one at the Neel temperature, T N =137 K, the other near 50 K. This suggests the coexistence of spin glass order and antiferromagnetism at this composition. These conclusions are supported by low-field magnetization measurements.