Characteristics of Graphitic Films for Carbon based Magnetism & Electronics

Department of Mechanical Engineering
Advisors: Sakhrat Khizroev & Qing Jiang

This dissertation concentrates on the characteristics of the graphene: single layer of graphite which is defined  as  two-dimensional  material  for  carbon  
based  magnetism  and  electronics.    Carbon  materials, which  are  demonstrated  by  diamond  and  graphite,  have  always  been  of  great  interest  for  their  unique properties.    Moreover,  in  the  last  two  decades,  there  have  been  three  revolutionary  milestones  in  the development  of  carbon  materials, which  were  related  to  the  discovery  of  fullerenes,  carbon  nanotubes, and  graphene,  respectively.    Such  research  evolution  led  to  the  realization  of  the  feasibility  to  tailor magnetic and electronic properties of graphiticsheets.  

Meanwhile,  magnetism  of  carbon  materials  is  of  particular  interest  because  of  its  new  and  relatively unexplored  origins.    The  technological  potential  of  the  new  materials  is  enormous  as  they  promise  to become  the  first  room-temperature  ferromagnetic  semiconductors  –  the  holy  grail of the world  of  electronics. Not  to  mention  that  the existence  of  the  new  materials  is  vital  for  the  emerging  field  of  spintronics. Researchers  are  convinced  that  the  new  carbon-based  magnetic  materials  could  greatly extend the limits of current technologies relying on magnetic and semiconductor properties.  In this work, the magnetic properties of pristine graphene and chemically modified graphene were mainly studied.  The chemical  functionalization  was  performed  by  covalent  attachment  of  aryl  groups to  the  basal  plane  of carbon atoms.  This chemical modification with nitrophenyl (NP) groups  was formed by covalent bonding to the conjugated carbon atoms. The functionalized samples were found to be in a mix of ferromagnetic and  antiferromagnetic  states  with  spins  aligned  in  the main  plane  at  room  temperature.    Based  on  the findings, this work studies the origins of the intrinsic magnetism and potential ways to tailor magnetism in graphene.    In  conclusion,  this  technology  has  great  potential  to  pave  a  way  to  the  next-generation technologies of high-speed and high-density nonvolatile memory, reconfigurable logic devices, computing, integrated magneto-optical devices, quantum information devices, and many others.