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postgraduate thesis: Electronic structures of impurity and orbital-resolved vortex core states in iron-selenide superconductors

TitleElectronic structures of impurity and orbital-resolved vortex core states in iron-selenide superconductors
Authors
Issue Date2014
PublisherThe University of Hong Kong (Pokfulam, Hong Kong)
Citation
Wang, Q. [王乾恩]. (2014). Electronic structures of impurity and orbital-resolved vortex core states in iron-selenide superconductors. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b5317029
AbstractWe study the effect of a single non-magnetic impurity and vortex core states in iron-selenide superconductors by solving the Bogoliubov-de Gennes equations self-consistently based on a three-orbital model. Various pairing symmetry are considered in the calculation. The impurity-induced in-gap bound states are found only for attractive impurity scattering potential, as in the cases of doping of Co or Ni, which is characterized by the strong particle-hole asymmetry, in the nodeless d_(x^2-y^2 ) wave pairing state. This property may be used to probe the pairing symmetry of iron-selenide 122-type superconductors. The orbital-resolved vortex core states of different pairing symmetries manifest themselves as distinguishable structures due to different behavior of the quasiparticle wavefunctions. The obtained vortices are classified by the invariant subgroups of the symmetry group of the meanfield Hamiltonian in the presence of magnetic field as isotropic s- and s±-wave vortices have G_5 symmetry for each orbital, whereas d_(x^2-y^2 ) wave vortices show G(* )¦6 symmetry for d_xzand d_yz orbitals and G(* )¦5 symmetry for d_xy orbital. In the case of d_(x^2-y^2 ) wave vortices, hybridized-pairing between d_xzand d_yz orbitals gives rise to a relative phase difference in terms of winding structures of vortices between these two orbitals and d_xy orbital, which is essentially caused by a transformation of co-representation of G(* )¦5 and G(* )¦6 subgroup. Calculation of particle densities show common charging feature of vortices in the cases of s± and d_(x^2-y^2 ) wave pairing states where the electron-like vortices are observed for d_xz and d_yz orbitals while hole-like vortices for d_xyorbital. The phase difference of orbital-resolved d_(x^2-y^2 ) wave vortices and their charging effects can be verified by further experimental observations.
DegreeDoctor of Philosophy
SubjectIron-based superconductors
Dept/ProgramPhysics
Persistent Identifierhttp://hdl.handle.net/10722/206433

 

DC FieldValueLanguage
dc.contributor.authorWang, Qianen-
dc.contributor.author王乾恩-
dc.date.accessioned2014-10-31T23:15:53Z-
dc.date.available2014-10-31T23:15:53Z-
dc.date.issued2014-
dc.identifier.citationWang, Q. [王乾恩]. (2014). Electronic structures of impurity and orbital-resolved vortex core states in iron-selenide superconductors. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b5317029-
dc.identifier.urihttp://hdl.handle.net/10722/206433-
dc.description.abstractWe study the effect of a single non-magnetic impurity and vortex core states in iron-selenide superconductors by solving the Bogoliubov-de Gennes equations self-consistently based on a three-orbital model. Various pairing symmetry are considered in the calculation. The impurity-induced in-gap bound states are found only for attractive impurity scattering potential, as in the cases of doping of Co or Ni, which is characterized by the strong particle-hole asymmetry, in the nodeless d_(x^2-y^2 ) wave pairing state. This property may be used to probe the pairing symmetry of iron-selenide 122-type superconductors. The orbital-resolved vortex core states of different pairing symmetries manifest themselves as distinguishable structures due to different behavior of the quasiparticle wavefunctions. The obtained vortices are classified by the invariant subgroups of the symmetry group of the meanfield Hamiltonian in the presence of magnetic field as isotropic s- and s±-wave vortices have G_5 symmetry for each orbital, whereas d_(x^2-y^2 ) wave vortices show G(* )¦6 symmetry for d_xzand d_yz orbitals and G(* )¦5 symmetry for d_xy orbital. In the case of d_(x^2-y^2 ) wave vortices, hybridized-pairing between d_xzand d_yz orbitals gives rise to a relative phase difference in terms of winding structures of vortices between these two orbitals and d_xy orbital, which is essentially caused by a transformation of co-representation of G(* )¦5 and G(* )¦6 subgroup. Calculation of particle densities show common charging feature of vortices in the cases of s± and d_(x^2-y^2 ) wave pairing states where the electron-like vortices are observed for d_xz and d_yz orbitals while hole-like vortices for d_xyorbital. The phase difference of orbital-resolved d_(x^2-y^2 ) wave vortices and their charging effects can be verified by further experimental observations.-
dc.languageeng-
dc.publisherThe University of Hong Kong (Pokfulam, Hong Kong)-
dc.relation.ispartofHKU Theses Online (HKUTO)-
dc.rightsCreative Commons: Attribution 3.0 Hong Kong License-
dc.rightsThe author retains all proprietary rights, (such as patent rights) and the right to use in future works.-
dc.subject.lcshIron-based superconductors-
dc.titleElectronic structures of impurity and orbital-resolved vortex core states in iron-selenide superconductors-
dc.typePG_Thesis-
dc.identifier.hkulb5317029-
dc.description.thesisnameDoctor of Philosophy-
dc.description.thesislevelDoctoral-
dc.description.thesisdisciplinePhysics-
dc.description.naturepublished_or_final_version-
dc.identifier.doi10.5353/th_b5317029-

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