Orbital fluctuation mechanism for superconductivity in iron-based compounds

Abstract

We propose orbital fluctuations in a multi-band ground state as the superconducting pairing mechanism in the new iron-based materials. We develop a general SU(4) theoretical framework for studying a two-orbital model and discuss a number of scenarios that may be operational within this orbital fluctuation paradigm. The orbital and spin symmetry of the superconducting order parameter is argued to be highly non-universal and dependent on the details of the underlying band structure. We introduce a minimal two-orbital model for the Fe-pnictides characterized by non-degenerate orbitals that strongly mix with each other. They correspond to the iron "d_xy" orbital and to an effective combination of "d_zx" and "d_zy", respectively. Using this effective model we perform RPA calculations of susceptibilities and effective pairing interactions. We find that spin and orbital fluctuations are, generally, strongly coupled and we identify the parameters that control this coupling as well as the relative strength of various channels.

expanded version, 9+ pages, 6 color figures

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Cited by in corpus (28)

• Microwave Penetration Depth and Quasiparticle Conductivity in PrFeAsO_1-y Single Crystals : Evidence for a Full-Gap Superconductor
• Orbital Order and Spontaneous Orthorhombicity in Iron Pnictides
• Two types of s-wave pairing due to magnetic and orbital fluctuations in the two-dimensional 16-band d-p model for iron-based superconductors
• Quasiparticle Heat Transport in Ba${}_{1-x}$K${}_x$Fe${}_2$As${}_2$: Evidence for a k-dependent Superconducting Gap without Nodes
• First-principles calculation of transition-metal impurities in LaFeAsO
• Orbital coupling and superconductivity in the iron pnictides
• Superconductivity from orbital nematic fluctuations
• Abrupt recovery of Fermi-liquid transport by the c-axis collapse in CaFe2(As1-xPx)2 single crystals
• Tight binding model for iron pnictides
• Doping Dependence of Spin Dynamics in Electron-Doped Ba(Fe1-xCox)2As2
• Identifying the `Fingerprint' of Antiferromagnetic Spin-Fluctuations on Iron-Pnictide Superconductivity
• Evidence for Orbital Order and its Relation to Superconductivity in FeSe0.4Te0.6
• Quantifying the role of antiferromagnetic fluctuations in the superconductivity of the doped Hubbard model
• Cooperative effects of Coulomb and electron-phonon interactions in the two-dimensional 16-band d-p model for iron-based superconductors
• Spin nematic fluctuations near a spin-density-wave phase
• Penetration depth, lower critical fields, and quasiparticle conductivity in Fe-arsenide superconductors
• A weak-coupling superconductivity in the electron doped NaFe${}_{0.95}$Co${}_{0.05}$As is revealed by ARPES
• Constrained weak-coupling superconductivity in multiband superconductors
• Structure of the pairing gap from orbital nematic fluctuations
• Electronic dispersion anomalies in the iron pnictide superconductor Ba_{1-x}K_xFe_2As_2
• Evidence for a two-fold symmetric superconducting gap in a monolayer of FeSe${}_{0.5}$Te${}_{0.5}$ on a topological insulator
• Fermi surfaces and Phase Stability of Ba(Fe${}_{1-x}$M${}_x$)${}_2$As${}_2$ (M=Co, Ni, Cu, Zn)
• Suppression of superconductivity by spin fluctuations in iron-based superconductors
• Dispersionless orbital excitations in (Li,Fe)OHFeSe superconductors
• The effect of spin fluctuations on the electronic structure in iron based superconductors
• Anisotropic inplane spin correlation in the parent and Co-doped BaFe2As2: a neutron scattering study
• Spin-fluctuation glue disfavors high-critical temperature of superconductivity?
• Metal-insulator transition and superconductivity in the two-orbital Hubbard-Holstein model for iron-based superconductors