Manipulating non-collinear antiferromagnetic order and thermal expansion behaviors in triangular lattice Mn₃Ag_1−xSn(Ge)_xN

Magnetic materials with non-collinear spin orderings provide an outstanding platform to probe spintronic phenomena owing to their strong spin-orbit coupling (SOC) and unique Berry phase. It is thus important to obtain a non-collinear antiferromagnetic (AFM) phase at room temperature (RT). Significantly, the discovery of novel materials with nearly zero thermal expansion (ZTE) property near RT is required and pursued for avoiding thermal stress and fracture in spintronic devices. Herein, the doping of Sn (Ge) at the Ag site in the triangular lattice Mn₃Ag_1-xSn(Ge)_xN compounds increases effectively the Néel point and makes the interesting non-collinear Γ^5g AFM phase exist above RT. The magnetic phase diagrams with Γ^5g phase up to 498 K were built by the combined analysis of neutron powder diffraction (NPD), magnetic measurements, electronic transport, and differential scanning calorimetry (DSC). The thermal expansion behaviors of Mn₃Ag_1-xSn(Ge)_xN were modulated, and the nearly ZTE above RT was achieved in Mn₃Ag_0.5Ge_0.5N within Γ^5g AFM ordering. Our findings offer an effective way to tailor the non-collinear AFM ordering and correlated thermal expansion behavior for potential use in the emerging field of thermal stress-free magnetic chip materials.