Figure 5. Proposed spin structure at a temperature lower than T_N2 and higher than T_Dy, referring to neutron scattering data available in literature.

(a) The spin structure projected on the ab-plane with the square pyramidal Mn³⁺-O²⁻ unit and octahedral Mn⁴⁺-O²⁻ unit shown in (b). The structural block A, composed of one Mn⁴⁺-O²⁻ octahedra connected by two Mn³⁺-O²⁻ pyramids roughly along the b-axis, is shown in (c). The structural block B, composed of one Mn⁴⁺-O²⁻ octahedra connected by two Dy³⁺ roughly along the b-axis, is shown in (d). The proposed polarizations P_MM and P_DM generated by the two types of blocks due to the symmetric exchange strictions, are labeled in (c) and (d), respectively.