ORIGINAL PAPER Study of magnetism in nano structures of graphene and functionalized graphene: a first principle study N Kumar 1 *, M Sharma 2 , J D Sharma 1 and P K Ahluwalia 2 1 Department of Physics, Shoolini University, Bajhol, Distt. Solan 173 212, Himachal Pradesh, India 2 Department of Physics, Himachal Pradesh University, Shimla 171005, India Received: 23 March 2014 / Accepted: 26 May 2014 Abstract: A first principle calculation has been performed to explore the magnetism in nano structures of graphene due to vacancies in carbon lattice and functionalized (hydrogenated) graphene due to vacancies in hydrogen lattice. Nano structures containing 50C atoms (5 9 5 9 1 super cell) have been considered. Using the method of numeric localized atomic orbitals, pseudo potentials and density functional theory, spin polarised electron density of states have been calculated and C–C bond lengths, C–C–C and H–C–C bond angles, formation energy and magnetic moment have been obtained. It has been found that due to defects (vacancies) in carbon lattice of pristine graphene, nano structure develops magnetic moment, which varies with the size of defect. A nano structure with four contiguous vacancies is found to have a magnetic moment of 2.0 l B . The nano structures of hydrogenated graphene also develop magnetic moment due to vacancies in hydrogen lattice , which varies with number and position of vacancies. A nano structure with half hydro- genated graphene obtained by removing all the hydrogen atoms from one side of graphane, (alternate vacancies in hydrogen lattice 50C25H atoms, graphone) is found to develop a large magnetic moment of 25.0 l B . Keywords: Graphene; DFT; SIESTA; Magnetic moment PACs Nos.: 73.22.Pr; 71.15.Mb; 75.20.Hr 1. Introduction The process of increasing speed, efficiency and storage space in electronic devices has reached a state at which silicon technology is severely constrained. This is partly due to low mobility of charge carrier in silicon and its poor compatibility with the elements of III and V groups in integrated circuits. Beside this, the fabrication of devices using the elements of III and V groups of periodic table is rather expensive. With discovery of graphene in 2004 [1], carbon electronics seem to have a bright future. This fol- lows in the last two decades with discoveries of new allotropic modifications of carbon and related nanostruc- tures. Graphene out of such allotropic forms, is a carbon based two-dimensional planar structure that can be viewed as a single layer of graphite and has been proposed as a versatile material for many potential applications due to many unique electronic and magnetic properties [2]. In addition to numerous experimental and theoretical studies on the physical properties of graphene and other 2D materials [3–7], efforts have also been devoted to synthe- size various types of derivatives of graphene. More recently, a 2D hydrocarbon in the family of honeycomb structure, namely graphane, is obtained by saturated functionalization of graphene with hydrogen. The gra- phane, has been proposed theoretically in 2007 [8] and its preparation followed in 2009 [9]. Hydrogenation of graphene is reversible [9], providing the flexibility to manipulate its coverage. For example, one can remove the hydrogen atoms from one side of graphane, while keeping the other side hydrogenated. This results in a half-hydro- genated graphene which is named ‘‘graphone’’ [10]. The study of magnetism in carbon based materials has been of considerable experimental and theoretical interest [11–19]. Recent experimental efforts that produce ferro- magnetically interacting carbon systems [20–23] have renewed the interest in carbon magnetism. The prospect of *Corresponding author, E-mail: naveenattri83@gmail.com Indian J Phys DOI 10.1007/s12648-014-0526-2 Ó 2014 IACS