Manipulating the Electronic and Magnetic Properties of Monolayer Electride Ca₂N by Hydrogenation

The electride materials with free-electron gas have attracted intensive attention both experimentally and theoretically. Here, we demonstrate the effective modulation of the electronic and magnetic properties of monolayer electride Ca 2 N by hydrogenation based on first-principles calculations. The adsorption of hydrogen atoms can drive the pristine monolayer Ca 2 N from a nonmagnetic (NM) metal to a NM semiconductor in the semihydrogenation condition (one-sided coverage) and further to a ferromagnetic half-metal in the fully hydrogenation condition (two-sided coverage). In the former case, the free-electron gas on both sides of the monolayer Ca 2 N disappears, resulting in a semiconducting phase with a modest band gap of 1.13 eV. In the latter case, there is a structural phase transition from the 1 × 1 periodicity to the 3 × 3 one because of Fermi surface nesting; meanwhile, the magnetic moment of 1.0 μ B per unit cell is induced by the p orbitals of N atoms. With these flexible properties, the hydrogenated monolayer electride Ca 2 N has promising potential applications in future electronic and spintronic devices.