Formation of partial energy gap below the structural phase transition and the rare-earth element substitution effect on infrared phonons in ReFeAsO (Re=La, Nd, and Sm)

Abstract

Single crystals of LaFeAsO, NdFeAsO, and SmFeAsO have been prepared by means of a NaAs flux growth technique and studied by optical spectroscopy measurements. We show that the spectral features corresponding to the partial energy gaps in the spin-density-wave (SDW) state are present below the structural phase transition. This indicates that the electronic state below the structural phase transition is already very close to that in the SDW state. We also show that in-plane infrared phonon modes display systematic shifts towards high frequency upon rare-earth element substitutions for La, suggesting a strong enhancement of the bonding strength. Furthermore, an asymmetric line-shape of the in-plane phonon mode is observed, implying the presence of an electron-phonon coupling effect in Fe-pnictides.

6 pages

References in corpus (22)

• Magnetic Order versus superconductivity in the Iron-based layered La(O1-xFx)FeAs systems
• LaFeAsO${}_{1-x}$F${}_x$: A low carrier density superconductor near itinerant magnetism
• Superconductivity at 41 K and its competition with spin-density-wave instability in layered CeO${}_{1-x}$F${}_x$FeAs
• Structural and magnetic phase diagram of CeFeAsO1-xFx and its relationship to high-temperature superconductivity
• Competing Orders and Spin-Density-Wave Instability in La(O${}_{1-x}$F${}_x$)FeAs
• Theory of Electron Nematic Order in LaOFeAs
• Superconductivity in iron-based F-doped layered quaternary compound Nd[O1-xFx]FeAs
• Effect of Structural Parameters on Superconductivity in Fluorine-Free LnFeAsO1-y (Ln=La,Nd)
• Is LaO${}_{1-x}$F${}_x$FeAs an electron-phonon superconductor ?
• Origin of the ~150 K Anomaly in LaOFeAs; Competing Antiferromagnetic Superexchange Interactions, Frustration, and Structural Phase Transition
• Ising and Spin orders in Iron-based Superconductors
• Phase transitions in LaFeAsO: structural, magnetic, elastic, and transport properties, heat capacity and Mossbauer spectra
• Origin of the spin density wave instability in AFe${}_2$As${}_2$ (A=Ba, Sr) as revealed by optical spectroscopy
• Antiferromagnetic superexchange interactions in LaOFeAs
• Single crystal of superconducting SmFeAsO1-xFy grown at high pressure
• Magnetic Order of the Iron Spins in NdOFeAs
• Flux growth at ambient pressure of millimeter-sized single crystals of LaFeAsO, LaFeAsO1-xFx, and LaFe1-xCoxAsO
• Hall effect and magnetoresistance in single crystals of NdFeAsO${}_{1-x}$F${}_x$
• Phonon anomaly in BaFe2As2
• Optical spectroscopy study on single crystalline LaFeAsO
• The optical phonon spectrum of SmFeAsO
• Optical study on the spin-density wave properties in single crystalline Na${}_{1-\delta }$FeAs

Cited by in corpus (14)

• Unprecedented anisotropic metallic state in BaFe2As2 revealed by optical spectroscopy
• Orbital Fluctuation Theory in Iron Pnictides: Effects of As-Fe-As Bond Angle, Isotope Substitution, and $Z^2$-Orbital Pocket on the Superconductivity
• Effect of Co doping on the in-plane anisotropy in the optical spectrum of underdoped Ba(Fe1-xCox)2As2
• Doping dependence of femtosecond quasi-particle relaxation dynamics in Ba(Fe,Co)_2As_2 single crystals: possible evidence for normal state nematic fluctuations
• Optical conductivity and Raman scattering of iron superconductors
• Electronic structure of BaNi${}_2$As${}_2$
• Phonon splitting and anomalous enhancement of infrared-active modes in BaFe${}_2$As${}_2$
• In-plane optical spectroscopy study on FeSe epitaxial thin film grown on SrTiO${}_3$ substrate
• Temperature dependent local structure of NdFeAsO1-xFx system using arsenic K-edge extended x-ray absorption fine structure
• Band structure reconstruction across nematic order in high quality FeSe single crystal as revealed by optical spectroscopy study
• Optical study of Dirac fermions and related phonon anomalies in antiferromagnetic compound CaFeAsF
• Phase competition in a one-dimensional three-orbital Hubbard-Holstein model
• Isotropic Quenched Disorder Triggers a Robust Nematic State in Electron-Doped Pnictides
• Temperature dependent As K-edge EXAFS studies of LaFe1-xCoxAsO (x = 0.0 and 0.11) single crystals