Ab initio studies of isolated hydrogen vacancies in graphane

Abstract

We present a density functional study of various hydrogen vacancies located on a single hexagonal ring of graphane (fully hydrogenated graphene) considering the e ects of charge states and the position of the Fermi level. We nd that uncharged vacancies that lead to a carbon sublattice balance are energetically favourable and are wide band gap systems just like pristine graphane. Vacancies that do create a sublattice imbalance introduce spin polarized states into the band gap, and exhibit a half-metallic behavior with a magnetic moment of 1.00 B per vacancy. The results show the possibility of using vacancies in graphane for novel spin-based applications. When charging such vacancy con gurations, the deep donor (+1/0) and deep ac-ceptor (0/-1) transition levels within the band gap are noted. We also note a half-metallic to metallic transition and a signi cant reduction of the induced magnetic moment due to both negative and positive charge doping. Keywords: vacancies, sublattice, density functional theory, charge state, magnetic moment.