Two-step magnetic ordering into a canted state in ferrimagnetic monoclinic Mn3As2

Highlights: • Magnetic structure of Mn₃As₂ determined from neutron powder diffraction measurements at 3K and 250K. • Mn₃As₂ orders ferrimagnetically along b-axis between 225K and 270K. • Mn spins cant away from b-axis to form a non-collinear magnetic structure below 225K. We report the magnetic structure of monoclinic Mn₃As₂ at 3K and 250K using neutron powder diffraction measurements. From magnetometry data, the Curie temperature of Mn₃As₂ was confirmed to be around 270K. Calorimetry analysis showed the presence of another transition at 225K. At 270K, Mn₃As₂ undergoes a $k=0$ ferrimagnetic ordering in the magnetic space group $C2/m$ (#12.58) with Mn moments pointing along b. Below 225K, there is a canting of Mn moments in the $ac$ plane which produces a multi-k non-collinear magnetic structure in space group $C2/c$ (#15.85). The components of Mn moments along b follow $k=0$ ordering and the components along a and c have $k=\left[00\frac{1}{2}\right]$ propagation vector. The change in the magnetic ground state with temperature provides a deeper insight into the factors that govern magnetic ordering in Mn–As compounds.