Transition Metal Adsorbed-Doped ZnO Monolayer: 2D Dilute Magnetic Semiconductor, Magnetic Mechanism, and Beyond 2D

As an improvement over organic or inorganic layered crystals, the synthetic monolayer ZnO(M) inherits semiconductivity and hostability from its bulk, yet it acts as a promising host for dilute magnetic semiconductors. Here, we report the electronic and magnetic properties of ZnO(M) doped with one 3d transition metal ion and simultaneously adsorbed with another 3d transition metal ion. Two sequences are studied, one where the dopant is fixed to Mn and the adsorbate is varied from Sc to Zn and another where the dopant and adsorbate are reversed. First-principles results show that the stable adsorbed-doped systems possess a lower bandgap energy than that of the host. System magnetic moments can be tuned to |5 - x |μ B , where x refers to the magnetic moment of the individual 3d atom. An interplay between superexchange and direct exchange yields a ferromagnetic system dually adsorbed-doped with Mn. In addition to a novel material design route, the magnetic interaction mechanism is found beyond two dimensions, having been identified for its three-dimensional bulk and zero-dimensional cluster counterparts.