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.

Nearly zero thermal expansion (NZTE) materials have a high dimensional stability with a less possibility producing thermal stress under variable-temperature environment. Therefore, they can be used in aerospace, microelectronics, optics, precision devices and other fields. Mn-based antiperovskite compounds Mn₃AX (A=metal or semiconductor element, X=N or C) have attracted recent attention due to their negative or nearly zero thermal expansion (NTE/NZTE) properties within a wide temperature range, isotropy and easy regulation. Mn₃AX compounds exhibit rich magnetic structures, and their NTE/NZTE properties are closely related to the magnetic phase transitions and intense lattice-spin correlation. The magnetic structure and magnetic phase transition can be changed via optimizing the composition, thus effectively regulating the thermal expansion behavior and obtaining other functional properties. The existing methods to obtain the wide temperature range NTE/NZTE properties mainly include the broadening of the NTE behavior in the magnetic phase transition temperature range, regulation of specific magnetic phases that critically affect negative/zero thermal expansion properties, and multi-phase composition of the materials with different thermal expansion coefficients. This review represented the experimental and theoretical studies on the regulation of abnormal thermal expansion behavior of Mn₃AX antiperovskite compounds in recent years. The effective regulation and in-depth analysis of the abnormal NTE/ZTE properties of Mn-based antiperovskite compounds can reveal the physical origin of the anomaly in thermal expansion, which can greatly promote the application of these materials. This review also summarized recent research progress on the regulation strategy and mechanism of the NTE/ZTE properties of Mn-based antiperovskite, and prospected the future direction in this field.