Two dimensional layered transition metal carbides and nitrides, owing to their unique electronic properties, have potential applications in novel low-dimensional spintronic devices. However, only a few materials with half metallic and easy axis in perpendicular direction make possible for practical applications in spintronics. Here, the electronic structure and magnetic anisotropy of Mn₂CXX’ (X, X' = F, Cl, Br, I) Janus monolayers are investigated by first-principles calculations. It is found that the Mn₂CXX′ Janus monolayers are half metallic, showing a high spin polarization at Fermi level. The magnetic anisotropy of Mn₂CXX′ monolayers can be modulated by replacing the adsorbed atoms. Mn₂CFCl, Mn₂CClI and Mn₂CClBr show easy axis in perpendicular direction, while the easy axis of Mn₂CFBr is in-plane direction. When biaxial strains are −2%, ±4 % and −6%, the easy axis direction of Mn₂CClI changes from out-of-plane to in-plane, where the total magnetic anisotropy of I atom can be regulated. The easy axis in in-plane direction comes from the hybridization between I-p_z and I-p_x orbital. However, the easy axis of Mn₂CClI maintains perpendicular direction at biaxial strains of 2 % and 6 %. The Mn₂CXX′ monolayers with half metallicity and easy axis in perpendicular direction have the potential applications in spintronic devices.

二维层状过渡金属碳化物和氮化物由于其独特的电子特性，在新型低维自旋电子器件中具有潜在的应用价值。然而，只有少数具有半金属和垂直方向易轴的材料才能在自旋电子学中实现实际应用。在这里，通过第一性原理计算研究了Mn ₂ C XX ' ( X , X ' = F, Cl, Br, I) Janus 单分子层的电子结构和磁各向异性。发现Mn ₂ C XX ' Janus 单层是半金属的，在费米能级显示出高自旋极化。Mn ₂ C XX的磁各向异性' 单层可以通过替换吸附的原子来调节。Mn ₂ CFCl、Mn ₂ CClI和Mn ₂ CClBr在垂直方向显示易轴，而Mn ₂ CFBr的易轴在面内方向。当双轴应变为-2%、±4%和-6%时，Mn ₂ CClI的易轴方向从面外变为面内，可以调节I原子的总磁各向异性。面内方向的易轴来自 I- p _z和 I- p _x轨道之间的杂化。然而，Mn ₂ CClI的易轴在 2% 和 6% 的双轴应变下保持垂直方向。锰₂ CXX ′ 具有半金属丰度和易轴垂直方向的单层在自旋电子器件中具有潜在的应用。