  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.
