Phase separation and zero thermal expansion in antiperovskite Mn₃Zn$_{0.77}$Mn$_{0.19}$N$_{0.94}$ : An in situ neutron diffraction investigation

The antiperovskite Mn₃Zn$_{0.77}$Mn$_{0.19}$N$_{0.94}$ was investigated by in situ neutron powder diffraction (NPD) in the temperature region 5-300 K. Here, a noncollinear-antiferromagnetic/collinear-ferrimagnetic phase separation (PS) showing different lattice parameters was firstly revealed in antiperovskites. The NPD results prove that the noncollinear antiferromagnetic phase, even coexisting with the collinear ferrimagnetic phase, could be responsible for the zero thermal expansion behavior of Mn₃Zn$_{0.77}$Mn$_{0.19}$N$_{0.94}$ below 110 K. These findings suggest that Mn₃ZnN based materials could open a new avenue for further exploring the noncollinear magnetic PS and correlated physical properties of antiperovskites.