Itinerancy enhanced quantum fluctuation of magnetic moments in iron-based superconductors

Abstract

We investigate the influence of itinerant carriers on dynamics and fluctuation of local moments in Fe-based superconductors, via linear spin-wave analysis of a spin-fermion model containing both itinerant and local degrees of freedom. Surprisingly against the common lore, instead of enhancing the ($\pi$,0) order, itinerant carriers with well nested Fermi surfaces is found to induce significant amount of \textit{spatial} and temporal quantum fluctuation that leads to the observed small ordered moment. Interestingly, the underlying mechanism is shown to be intra-pocket nesting-associated long-range coupling, rather than the previously believed ferromagnetic double-exchange effect. This challenges the validity of ferromagnetically compensated first-neighbor coupling reported from short-range fitting to the experimental dispersion, which turns out to result instead from the ferro-orbital order that is also found instrumental in stabilizing the magnetic order.

6 pages, 3 figures, submitted to Phys. Rev. Lett. on 17 September 2014

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• Pressure Driven Fractionalization of Ionic Spins Results in Cupratelike High-$T_c$ Superconductivity in La${}_3$Ni${}_2$O${}_7$
• Orbital Origin of Extremely Anisotropic Superconducting Gap in Nematic Phase of FeSe Superconductor
• Pressure-driven phase transition from antiferromagnetic semiconductor to nonmagnetic metal in two-leg ladders $A$Fe${}_2$$X$${}_3$ ($A$=Ba or K, $X$=S or Se)
• Antiferromagnetic order in epitaxial FeSe films on SrTiO3
• Trilayer multi-orbital models of $\mathrm{L}{\mathrm{a}}_4\mathrm{N}{\mathrm{i}}_3{\mathrm{O}}_{10}$
• Unified phase diagram for iron-based superconductors
• Characteristic Timescales of the Local Moment Dynamics in Hund's-metals
• Incommensurate smectic phase in close proximity to the high-Tc superconductor FeSe/SrTiO3
• How to read between the lines of electronic spectra: the diagnostics of fluctuations in strongly correlated electron systems
• Robust short-range-ordered nematicity in FeSe evidenced by high-pressure NMR
• Study of multiband disordered systems using the typical medium dynamical cluster approximation
• Thermal evolution of antiferromagnetic correlations and tetrahedral bond angles in superconducting FeTe${}_{1-x}$Se${}_x$
• Neutron powder diffraction study on the iron-based nitride superconductor ThFeAsN
• Magnetic moment evolution and spin freezing in doped BaFe${}_2$As${}_2$
• Dimensionality, nematicity and Superconductivity in Fe-based systems
• Driving force of the orbital-relevant electronic nematicity in Fe-based superconductors
• Spin dynamics of the spin chain antiferromagnet RbFeS${}_2$
• Phase transitions in a frustrated biquadratic Heisenberg model with coupled orbital degree of freedom for iron-based superconductors
• Stronger quantum fluctuation with larger spins: Emergent magnetism in the pressurized high-temperature superconductor FeSe
• Distinct Nature of Orbital Selective Mott Phases Dominated by the Low-energy Local Spin Fluctuations
• Effective Ionic Valence and Local Magnetic Moment in Kagome Superconductors