Novel Magnetic Block States in Low-Dimensional Iron-Based Superconductors

Magnetic states of the five-orbital Hubbard model for one-dimensional iron-based superconductors

The magnetic phase diagrams of models for quasi-one-dimensional compounds belonging to the ironbased-superconductor family are presented. The five-orbital Hubbard model and the real-space Hartree–Fock approximation are employed, supplemented by density functional theory to obtain the hopping amplitudes. Phase diagrams are constructed by varying the Hubbard U and Hund J couplings at zero tempera...

Magnetic Interactions in Low-Dimensional Iron Nanostructures

Unified picture for magnetic correlations in iron-based superconductors.

The varying metallic antiferromagnetic correlations observed in iron-based superconductors are unified in a model consisting of both itinerant electrons and localized spins. The decisive factor is found to be the sensitive competition between the superexchange antiferromagnetism and the orbital-degenerate double-exchange ferromagnetism. Our results reveal the crucial role of Hund's rule couplin...

Magnetic excitations in iron chalcogenide superconductors.

Nuclear magnetic resonance and neutron scattering experiments in iron chalcogenide superconductors are reviewed to make a survey of the magnetic excitations in FeSe, FeSe1-x Te x and alkali-metal-doped Ax Fe2-y Se2 (A = K, Rb, Cs, etc). In FeSe, the intimate relationship between the spin fluctuations and superconductivity can be seen universally for the variations in the off-stoichiometry, the ...

Magnetic properties of the superconducting state of iron-based superconductors

We show that features of the dynamical spin susceptibility can unambiguously distinguish between different pairing symmetries of the superconducting state in iron-based superconductors. A magnetic resonance is a feature for the extended sx2y2-wave cos kx cos ky pairing symmetry. It is present in the pure superconducting SC state but weakens in the mixed SC and magnetically ordered state. We cal...