Superconductivity and Anti Ferromagnetic Spin Density wave in Iron based Superconductors
| dc.contributor.author | Kitachew, Girma | |
| dc.date.accessioned | 2018-06-26T10:53:30Z | |
| dc.date.accessioned | 2023-11-09T11:23:38Z | |
| dc.date.available | 2018-06-26T10:53:30Z | |
| dc.date.available | 2023-11-09T11:23:38Z | |
| dc.date.issued | 2015-01 | |
| dc.description.abstract | The interplay between magnetism and superconductivity had attracted immence interest and effort following the discovery of magnetic superconductors like heavy fermion, cuprate and recent iron based superconductors (FebSC). The study of their interplay between has also been fascinating area of study due to complex magnetic interactions in the systems. In the latest, FebSCs the competition between antiferromagnetic (AFM) spin density wave (SDW) and superconductivity (SC) has attracted considerable attention in the current research in the field of superconductivity. The magnetic order in most FebSCs is the result of nesting between hole and electron pockets found at the the center and corners of the unfolded Brillouin zones. The interaction between fermions forming these pockets is important to study the low temperature physics of FebSCs. The model Hamiltonian consisting of these fermions responsible for magnetic and superconducting pairing interactions is developed to study their interplay. Using either Green function or Bogoligiv transformation method gap equations for SDW and s- wave superconductivity order parameters have been established for pure systems and for interacting ones. The gap equations have been studied in detail as physically accepted choice of parameters. We have established experimentally accepted Electronic Phase diagrams for some FebSCs. First we study the interplay between sign reversal s-wave symmetry superconductivity (SC+-) and SDW order parameters and found their homogeneous microscopic coexistence in under doped region. On the other hand the competition between sign preserving s-wave superconductivity (SC++) and SDW order parameters produce their homogeneous overlap near quantum critical point which is vi ABSTRACT consistent with the phase diagram of electron doped LaFeAsF compounds. When the magnetic order is commensurate SDW (SDWc) the interplay calculation presents the first order transition from SDW to SC++ which is consistent with the phase separated doped FebSCs compounds like doped Li Fe As compounds. The first model calculation results can be compared with the experimental report of doped Ba Fe2 As2 iron based families, doped Sm Fe AsO and electron doped LaFe As compounds. Even more interestingly, the result of our study showed first order transition from SDWc to incommensurate SDW (SDWδ) which is directly related to the observed magnetic orders near optimal doped region of Ba Fe2 As2. The strong suppression of SDW order parameter in the SC phases and the suppression of superconductivity in both under doped and over doped regions are some of the interesting results | en_US |
| dc.identifier.uri | http://10.90.10.223:4000/handle/123456789/3691 | |
| dc.language.iso | en | en_US |
| dc.publisher | Addis Ababa University | en_US |
| dc.subject | Iron based Superconductors | en_US |
| dc.title | Superconductivity and Anti Ferromagnetic Spin Density wave in Iron based Superconductors | en_US |
| dc.type | Thesis | en_US |