title: Electronic Structures of Clusters of Hydrogen Vacancies on Graphene.
abstract: Hydrogen vacancies in graphane are products of incomplete hydrogenation of graphene. The missing H atoms can alter the electronic structure of graphane and therefore tune the electronic, magnetic, and optical properties of the composite. We systematically studied a variety of well-separated clusters of hydrogen vacancies in graphane, including the geometrical shapes of triangles, parallelograms, hexagons, and rectangles, by first-principles density functional calculation. The results indicate that energy levels caused by the missing H are generated in the broad band gap of pure graphane. All triangular clusters of H vacancies are magnetic, the larger the triangle the higher the magnetic moment. The defect levels introduced by the missing H in triangular and parallelogram clusters are spin-polarized and can find application in optical transition. Parallelograms and open-ended rectangles are antiferromagnetic and can be used for nanoscale registration of digital information.
authors.affiliation: Department of Natural science, Center for General Education, Chang Gung University, Kueishan 333, Taiwan, ROC.
authors.forename: Bi-Ru
authors.initials: BR
authors.lastname: Wu
authors.affiliation: Graduate Institute of Applied Physics, National Chengchi University, Taipei 11605, Taiwan, ROC.
authors.forename: Chih-Kai
authors.initials: CK
authors.lastname: Yang