Transition between half-metal and ferromagnetic semiconductor induced by silicon vacancy in epitaxial silicene

Since the inevitability in experimental synthesis, defects show great importance to many materials. They will deeply regulate the properties of the materials, and then affect the further applications. Thus, exploring the effects of defects on the properties of materials is desired. Here, by using first-principles calculations, we systematically studied the effect of silicon vacancy defects on the properties of silicene generated on Nterminated cubic boron nitride (111) surface. It is found that the introduction of silicon vacancy would trigger transition between half-metal and ferromagnetic semiconductor. With small vacancy ratios of 1/36 and 1/24, the ground-state of the samples would behave as ferromagnetic semiconductors, and the band gaps are about 1.25 and 0.95 eV, respectively. When the vacancy ratio is increased up to 1/6, the sample would turn into a ferromagnetic half-metal with a half-metallic gap of around 0.15 eV. The change of the electronic structure of the samples is driven by the different electron transfer between silicon layer and substrate, i.e., there will be different amount of electrons transferred from the silicon layer to the substrate when the vacancy ratio is altered. This work would open a new way to regulate the properties of materials and extend applications in nanoelectronic field.