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 Ca2N by hydrogenation based on first-principles calculations. The adsorption of hydrogen atoms can drive the pristine monolayer Ca2N 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 Ca2N 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 μB per unit cell is induced by the p orbitals of N atoms. With these flexible properties, the hydrogenated monolayer electride Ca2N has promising potential applications in future electronic and spintronic devices.