Abstract:
We perform ab initio density functional theory calculations to investigate the energetics,
electronic and magnetic properties of isolated stoichiometric and non-stoichiometric
substitutional Si complexes in a hexagonal boron-nitride monolayer. The Si impurity atoms
substituting the boron atom sites SiB giving non-stoichiometric complexes are found to be
the most energetically favourable, and are half-metallic and order ferromagnetically in the
neutral charge state. We find that the magnetic moments and magnetization energies increase
monotonically when Si defects form a cluster. Partial density of states and standard Mulliken
population analysis indicate that the half-metallic character and magnetic moments mainly
arise from the Si 3p impurity states. The stoichiometric Si complexes are energetically
unfavorable and non-magnetic. When charging the energetically favourable non-stoichiometric
Si complexes, we find that the formation energies strongly depend on the impurity charge
states and Fermi level position. We also find that the magnetic moments and orderings are
tunable by charge state modulation q = −2, −1, 0, +1, +2. The induced half-metallic
character is lost (retained) when charging isolated (clustered) Si defect(s). This underlines the
potential of a Si doped hexagonal boron-nitride monolayer for novel spin-based applications.
