Magnetism in CeFeAsO1−xFx and LaFeAsO1−xFx from first principles

Competition/Coexisitence of Magnetism and Superconductivity in Iron Pnictides Probed by Muon Spin Rotation

The presence of macroscopic phase separation into superconducting and magnetic phases in LaFeAsO1−xFx and CaFe1−xCoxAsF is demonstrated by muon spin rotation (μSR) measurement across their phase boundaries (x = 0.06 for LaFeAsO1−xFx and x = 0.075–0.15 for CaFe1−xCoxAsF). In LaFeAsO0.94F0.06, both magnetism and superconductivity develop simultaneously below a common critical temperature, Tm ≃ Tc...

Flux growth at ambient pressure of millimeter-sized single crystals of LaFeAsO, LaFeAsO1−xFx, and LaFe1−xCoxAsO

Millimeter-sized single crystals of LaFeAsO, LaFeAsO1−xFx, and LaFe1−xCoxAsO were grown in NaAs flux at ambient pressure. The detailed growth procedure and crystal characterizations are reported. The as-grown crystals have typical dimensions of3×4×0.05–0.3 mm3 with the crystallographic c-axis perpendicular to the plane of the platelike single crystals. Various characterizations confirmed the hi...

Density-functional calculations of the electronic structures and magnetism of the pnictide superconductors BaFeAs2 and BaFeSb2

We investigate the structural, electronic, and magnetic properties of the hypothetical compound BaFePn2 Pn=As and Sb , which is isostructural to the parent compound of the high-temperature superconductor LaFeAsO1−xFx. Using density-functional theory, we show that the Fermi surface, electronic structure, and spin-density wave instability of BaFePn2 are very similar to the Fe-based superconductor...

Unconventional pairing originating from the disconnected Fermi surfaces of superconducting LaFeAsO1-xFx.

For a newly discovered iron-based high T_{c} superconductor LaFeAsO1-xFx, we have constructed a minimal model, where inclusion of all five Fe d bands is found to be necessary. The random-phase approximation is applied to the model to investigate the origin of superconductivity. We conclude that the multiple spin-fluctuation modes arising from the nesting across the disconnected Fermi surfaces r...

Element-Specific Phonon Density of States of Iron in LaFeAsO1-xFx and La1-xCaxFePO