2010/07/31 by Junhua Zhang, Rastko Sknepnek, Jörg Schmalian · 30 citations
Business, Management and Accounting · Materials Science · Physics and Astronomy · #Anisotropy #Antiferromagnetism #Condensed matter physics #Corporate Taxation and Avoidance #Inelastic neutron scattering #Iron-based superconductors research #Neutron scattering #Physics #Quantum mechanics #Scattering #Spin (aerodynamics) #Superconductivity #cond-mat.str-el #cond-mat.supr-con
paper · pdf · doi:10.1103/physrevb.82.134527
published in Physical Review B 82(13) (American Physical Society) · 9 pages, 8 figures
openalex publication_date 2010/10/20 · arxiv created 2010/10/21 · arxiv updated 2010/10/25 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Spin fluctuations are considered to be one of the candidates that drive a sign-reversed s^\ifmmode±\else\textpm\fi superconducting state in the iron pnictides. In the magnetic scenario, whether the spin-fluctuation spectrum exhibits certain unique fine structures is an interesting aspect for theoretical study in order to understand experimental observations. We investigate the detailed momentum dependence of the short-range spin fluctuations using a two-orbital model in the self-consistent fluctuation exchange approximation and find that a common feature of those fluctuations that are capable of inducing a fully gapped s^\ifmmode±\else\textpm\fi state is the momentum anisotropy with lengthened span along the direction transverse to the antiferromagnetic momentum transfer. Performing a qualitative analysis based on the orbital character and the deviation from perfect nesting of the electronic structure for the two-orbital and a more complete five-orbital model, we gain the insight that this type of anisotropic spin fluctuations favor superconductivity due to their enhancement of intraorbital, but interband, pair scattering processes. The momentum anisotropy leads to elliptically shaped magnetic responses which have been observed in inelastic neutron-scattering measurements. Meanwhile, our detailed study on the magnetic and the electronic spectrum shows that the dispersion of the magnetic resonance mode in the nearly isotropic s^\ifmmode±\else\textpm\fi superconducting state exhibits anisotropic propagating behavior in an upward pattern and the coupling of the resonance mode to fermions leads to a dip feature in the spectral function.