Theoretical Prediction of the Robust Intrinsic Half-Metallicity in Ni2N MXene with Different Types of Surface Terminations

Bare and surface-passivated Fe2N, Co2N, and Ni2N MXene were investigated by using density functional theory. Fe2N(OH)2, Fe2NO2, Co2NO2, Ni2NF2, Ni2N(OH)2, and Ni2NO2 are intrinsic half-metals, while other structures have antiferromagnetic ground states. The half-metallicity of Ni2NT2 (T = F, OH, and O) does not depend on the type of surface terminations and should be more realizable in experiments. The energy differences between the ferromagnetic and antiferromagnetic configurations of Ni2NT2 are several hundreds of meV per primitive cell. The Curie temperature should be above room temperature from the point of view of mean field approximation.