Semi-hydrogenated polyaniline sheet: A half-metal with exotic properties

Abstract Polyaniline sheet has been recently synthesized experimentally and attracted a lot of attention due to its exotic properties. In this research, we study electrical properties of semi-hydrogenated polyaniline sheet, SHP, in details. First-principle calculations reveal that the SHP is a half-metal with spin polarization of 100 % . The magnetization is attributed to the localized p z electronic orbitals of unsaturated carbon atoms and half-metallicity is related to the nitrogen atoms. Phonon band structure confirms the sheet is dynamically stable and ab initio molecular dynamics simulations indicate the sheet can be synthesized at room temperature. Tensile biaxial strain improves the half-metallicity of the sheet so that a 70 % increase in the band gap of spin-up is observed when a 12 % tensile strain is applied. The substrate can moderate the magnetization of two-dimensional materials. Our analysis reveals the sheet grown on the hexagonal boron-nitride sheet is still a half-metal. A transition from half-metal to magnetic metal is observed when the sheet is grown on the Si(1 1 1) substrate due to strong bonds between some unsaturated carbon atoms with top Si atoms. In addition, we show that the sheet can preserve its half-metallicity under hydrogen vacancy. Our findings show that semi-hydrogenated polyaniline sheet has a great potential for spintronics and spin-filtering.