Transition from antiferromagnetic ground state to robust ferrimagnetic order with Curie temperatures above 420 K in manganese-based antiperovskite-type structures

Manganese (Mn)-based antiperovskite structures (Mn ₃ AX, where A and X represent the 3d transition-metal elements and N or C atoms, respectively) have attracted growing attention because of their novel electronic and magnetic properties. However, the lack of an effective approach to regulate the magnetic coupling in Mn ₃ AX crystal structure, particularly in antiferromagnetic ground states, hinders their further design and applications. Herein, robust high-temperature ferrimagnetic order with a Curie temperature (T _C ) in the range of ∼390-420 K was successfully achieved in Mn ₃ Ga _x N _x (x = 0.5, 0.6, and 0.7) via composition-deficient engineering. A systematic investigation, including synchrotron X-ray diffraction, neutron powder diffraction, pair distribution function, X-ray absorption near-edge structure, magnetic characterization, and first-principles calculations, convincingly indicated that the redistribution of partial atoms in the antiferromagnetic ground state was responsible for the observed long-range magnetic order. These results not only provide a new perspective into the design and construction of high-temperature ferrimagnets based on the Mn ₃ AX structure, but also open up a promising avenue for the further design of Mn ₃ AX-based spintronic or other multifunctional devices.