Ni-doping effect on the magnetic transition and correlated lattice contraction in antiperovskite Mn ₃ZnN compounds

The Ni-doping effect on the lattice and magnetic properties in Mn ₃Zn _1-xNi _xN was first reported. The ground-state magnetic structure for Mn ₃ZnN is noncollinear antiferromagnetic Γ5 ^g. The introduction of Ni-doping induces a continuous spin rotation in the (111) plane from Γ5 ^g to weak ferromagnetic Γ4 ^g configurations, exhibiting a change from antiferromagnetic to weak ferromagnetic with increasing Ni content. In particular, when Ni content increased to x<0.5, Mn ₃Zn _1-xNi _xN shows an abrupt lattice contraction near the magnetic transition with increasing temperature. The normalabnormal lattice variation in Mn ₃Zn _1-xNi _xN is explained by the competition between the negative free energy variation δ ^Fe and the positive δ ^F0.