Magnetic and electronic properties of silicane with hydrogen vacancies on the surface

► Controllable magnetism can be obtained by creating H vacancies on the silicane surface. ► The spins of unsaturated Si in the single-sided domain are ferromagnetically ordered. ► In contrast, the double-sided domain is anti-ferromagnetic. ► The creation of H vacancies induces additional flat bands in the original band structure. ► The band gap can be manipulated by changing the size and/or shape of a certain domain. By using first-principles pseudopotential calculations, we investigate the magnetic and electronic properties of hydrosilicon honeycomb structure (silicane) with hydrogen vacancies on its surface. It is found that a single vacancy created on the nonmagnetic silicane can induce a magnetic moment of one μB. When a domain of vacancies is considered, the magnetization is determined by the size and geometry of the domain, and whether it is single- or double-sided. Compared with the energy band structure of silicane, the creation of domain causes very flat bands around the Fermi level and tends to reduce the band gap. It is interesting to find that the systems with single-sided domain all exhibit a band gap of about 1.0eV while those of double-sided domain exhibit strong size dependence.