Two-dimensional semi-metallic Luttinger compensated magnetic materials Mn₂NX (X = F, Cl) with ferroelasticity

As with altermagnetism, the theoretical prediction of fully compensated ferrimagnetism, which exhibits band spin splitting yet has a zero net magnetization, has yet to be validated experimentally. In this work, a new class of Luttinger-compensated ferrimagnetic semimetals, Mn₂NX (X = F and Cl) monolayers, have been identified theoretically through first-principles calculations. They are dynamically, thermally, and mechanically stable. Magnetic ions with opposite spin lattices cannot be connected by any symmetry. Consequently, the bands exhibit spin-splitting, yet the total magnetic moment remains zero. Mn₂NX systems exhibit a Néel temperature (T_N) approaching room temperature, in-plane auxiticity, and anisotropic ultrafast Fermi velocities. Furthermore, Mn₂NX materials exhibit ferroelasticity with moderate switching barriers and low reversible strain. The in-plane anisotropic properties are modulated by the 90° ferroelastic transition. Our work enriches Luttinger-compensated ferrimagnetic materials, providing an ideal opportunity to examine their unique physical properties and potential applications in spintronic devices.