Mn2C monolayer: a 2D antiferromagnetic metal with high Néel temperature and large spin-orbit coupling

To realize antiferromagnetic spintronics in the nanoscale, it is highly desirable to identify new nanometer-scale antiferromagnetic metals with both high Néel temperature and large spin-orbit coupling. In this work, on the basis of first-principles calculation and particle swarm optimization (PSO) global structure search, we demonstrate that a two-dimensional Mn₂C monolayer is an antiferromagnetic metal with a Mn magnetic moment of ~3μ_B. Mn₂C monolayer has an anti-site structure of MoS₂ sheet with carbon atoms hexagonally coordinated by neighboring Mn atoms. Remarkably, the in-plane carrier mobility of 2D Mn₂C is highly anisotropic, amounting to about 47 000 cm² V^-1 s^-1 in the a' direction, which is much higher than that of MoS₂ monolayer. The Néel temperature of Mn₂C monolayer is high up to 720 K. Due to strong spin-orbit coupling in plane, the magnetic anisotropy energy of Mn₂C monolayer is larger than those of pure metals, such as Fe, Co, and Ni. These advantages render 2D Mn₂C sheet with great potential applications in nanometer-scale antiferromagnetic spintronics.To realize antiferromagnetic spintronics in the nanoscale, it is highly desirable to identify new nanometer-scale antiferromagnetic metals with both high Néel temperature and large spin-orbit coupling. In this work, on the basis of first-principles calculation and particle swarm optimization (PSO) global structure search, we demonstrate that a two-dimensional Mn₂C monolayer is an antiferromagnetic metal with a Mn magnetic moment of ~3μ_B. Mn₂C monolayer has an anti-site structure of MoS₂ sheet with carbon atoms hexagonally coordinated by neighboring Mn atoms. Remarkably, the in-plane carrier mobility of 2D Mn₂C is highly anisotropic, amounting to about 47 000 cm² V^-1 s^-1 in the a' direction, which is much higher than that of MoS₂ monolayer. The Néel temperature of Mn₂C monolayer is high up to 720 K. Due to strong spin-orbit coupling in plane, the magnetic anisotropy energy of Mn₂C monolayer is larger than those of pure metals, such as Fe, Co, and Ni. These advantages render 2D Mn₂C sheet with great potential applications in nanometer-scale antiferromagnetic spintronics.

Electronic supplementary information (ESI) available: Bonding structure of the Mn₂C monolayer. The optimized structure and phonon spectrum of the Mn₂C-II monolayer. See DOI: 10.1039/c6nr02417c.