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Design of Graphene Spintronic Devices

Barami, Soode | 2013

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 44771 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Faez, Rahim
  7. Abstract:
  8. Magnetization have an important role in spintronic devices based on graphene. In this study the effect of stone-wales and vacancy defect on electrical and magnetic properties of zigzag and armchair graphene nanoribbons were investigated. Calculations are performed using tight-binding and hubard model combining with Green's function techniques. When the balance between A and B sub-lattices gets disturbed, magnetization will be appeared. In stone-wales defect we have local magnetization because of changing the position of sub-lattices and the total magnetization is zero. In addition the stone-wales defect can change and modify the band structures and band gaps. Vacancy of carbon atom in graphene nanoribbons is an other way too see magnetization in these structures. Magnetization will be changed depend on the position of vacancy. With introducing mono vacancy in edge (center) of zigzag graphene nanoribbon, the magnet moment of 0.08 μ_B (0.2918 μ_B) is obtained. For armchair graphene nanoribbon with mono vacancy in edge and center the magnet moment of 0.1161μ_Band 0.1338μ_Bare earned respectively. If the localized vacancy states are in the middle of nanoribbon, their effect on the magnetization and band structures will be maximum. Once the vacancy is moved toward one edge, the number of less affecting atoms on band structures of the nanoribbon increases compared to when the vacancy is in the middle of nanoribbon and magnetization is decreased
  9. Keywords:
  10. State Density ; Energy Gap ; Spintronic Devices ; Graphene Nanoribbons ; Band Structure ; Magnetism ; Tight Binding Method ; Hubbard Model

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