Neutron Studies of the Iron-based Family of High TC Magnetic Superconductors

Abstract

We review neutron scattering investigations of the crystal structures, magnetic structures, and spin dynamics of the iron-based RFe(As,P)O (R=La, Ce, Pr, Nd), (Ba,Sr,Ca)Fe2As2, and Fe1+x(Te-Se) systems. On cooling from room temperature all the undoped materials exhibit universal behavior, where a tetragonal-to-orthorhombic/monoclinic structural transition occurs, below which the systems become antiferromagnets. For the first two classes of materials the magnetic structure within the a-b plane consists of chains of parallel Fe spins that are coupled antiferromagnetically in the orthogonal direction, with an ordered moment typically less than one Bohr magneton. Hence these are itinerant electron magnets, with a spin structure that is consistent with Fermi-surface nesting and a very energetic spin wave bandwidth ~0.2 eV. With doping, the structural and magnetic transitions are suppressed in favor of superconductivity. Magnetic correlations are observed in the superconducting regime, with a magnetic resonance that follows the superconducting order parameter just like the cuprates. The rare-earth moments order antiferromagnetically at low T like conventional magnetic-superconductors. Pressure in CaFe2As2 transforms the system from a magnetically ordered orthorhombic material to a collapsed non-magnetic tetragonal system. Tetragonal Fe1+xTe transforms to a low T monoclinic structure at small x that changes to orthorhombic at larger x, which is accompanied by a crossover from commensurate to incommensurate magnetic order. Se doping suppresses the magnetic order.

Review of Neutron work on the structure & magnetic properties, Final version for Physics C

References in corpus (1)

• Electronic Structure of Fe-Based Superconductors

Cited by in corpus (37)

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• Neutron and ARPES Constraints on the Couplings of the Multiorbital Hubbard Model for the Pnictides
• Spin excitations in the excitonic spin-density-wave state of the iron pnictides
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• Magnetic excitations of Fe_{1+y}Se_xTe_{1-x} in magnetic and superconductive phases
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• Spin waves and magnetic exchange interactions in the spin ladder compound RbFe${}_2$Se${}_3$
• Analysis of spin density wave conductivity spectra of iron pnictides in the framework of density functional theory
• Effect of Li-deficiency impurities on the electron-overdoped LiFeAs superconductor
• Antiferromagnetic spin excitations in single crystals of nonsuperconducting Li1-xFeAs
• Incommensurate antiferromagnetic fluctuations in single-crystalline LiFeAs studied by inelastic neutron scattering
• Eliashberg Analysis of Optical Spectra Reveals Strong Coupling of Charge Carriers to Spin Fluctuations in Superconducting Iron Pnictides
• Strong ferromagnetic exchange interaction in the parent state of the superconductivity in BaFe${}_2$S${}_3$
• The evolution of antiferromagnetic susceptibility to uniaxial pressure in Ba(Fe{1-x}Co{x})2As2
• Magnetic and structural transitions in La${}_{0.4}$Na${}_{0.6}$Fe${}_2$As${}_2$ single crystals
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• Commensurate antiferromagnetic ordering in Ba(Fe{1-x}Co{x})2As2 determined by x-ray resonant magnetic scattering at the Fe K-edge
• Magnetic order tuned by Cu substitution in Fe1.1-zCuzTe
• Spin excitations in K${}_2$Fe${}_{4+x}$Se${}_5$: linear response approach
• Suppression of magnetic order in CaCo${}_{1.86}$As${}_2$ with Fe substitution: Magnetization, neutron diffraction, and x-ray diffraction studies of Ca(Co${}_{1-x}$Fe${}_x$)${}_y$As${}_2$
• Magnetism in Na-filled Fe-based skutterudites
• High pressure transport studies of the LiFeAs analogues CuFeTe2 and Fe2As
• Non-superconducting electronic ground state in pressurized BaFe${}_2$S${}_3$ and BaFe${}_2$S${}_{2.5}$Se${}_{0.5}$
• Antiferromagnetic Stacking of Ferromagnetic Layers and Doping Controlled Phase Competition in Ca${}_{1-x}$Sr${}_x$Co${}_{2-y}$As${}_2$
• Magnetic neutron scattering studies on the Fe-based superconductor system Fe${}_{1+y}$Te${}_{1-x}$Se${}_x$
• Tuning the magnetic and structural phase transitions of PrFeAsO via Fe/Ru spin dilution
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• The symplectic-N t-J model and s${}_{\pm }$ superconductors
• Impurity effects on spin dynamics in magnetic and superconducting iron pnictides and chalcogenides
• Persistent Magnetism in Silver-doped BaFe2As2 Crystals