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Effect of Co Doping on Crystal and Electronic Structure of BaFe2-xCoxAs2

Shafiei, Manouchehr | 2014

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 46026 (04)
  4. University: Sharif University of Technology
  5. Department: Physics
  6. Advisor(s): Khosroabadi, Hossein; Akhavan, Mohammad
  7. Abstract:
  8. The discovery of the iron-based superconductors attracted much experimental and theoretical attention in the recent years. BaFe2As2 is one of the highlighted materials which is the antiferromagnetic metal (below Neel temperature) and undergoes to superconducting and non-magnetic state by variety of doping, usually accompanied by a structural phase transition. Superconductivity is appeared in this system by doping Co and Ni at the Fe sites which is one of the excited situations in the physics of superconductors, where the magnetic doping suppresses the superconducting state. So, the study of Co doping of the electronic structure of this system, might lead us to better understanding of the role of magnetic doping elements and the underlying physics of superconductivity in these systems. We have investigated the effect of substitution of Co at the Fe site on structure and electronic structure of BaFe2-xCoxAs2 (x = 0, 1, 2). Ab-initio density functional theory by using of pseudopotential Quantum Espresso code in the generalized gradient approximation has been used for this study. Optimization calculations are performed for obtaining equilibrium value of lattice parameters and internal coordinates of ions. Results of these calculations are in agreement with the other computational and experimental data. Also, the total and partial density of states, band structure and Fermi surface of the three compounds have been calculated and compared together to find the role of Co doping on the electronic structure of this systems. Their results show that one of the important effects by Co substitution is the band rigid shifting downward relative to the Fermi level.
  9. Keywords:
  10. Electron Structure ; Density Functional Theory (DFT) ; Fermi Level ; Iron Based Superconductor ; Psuedopotentials ; Crystalline Structure

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