Related papers: Optical spectroscopy study on single crystalline L…

We report an optical investigation on the in-plane charge dynamics for Na$_{1-\delta}$FeAs single crystal. A clear optical evidence for the spin-density wave (SDW) gap is observed. As the structural/magnetic transitions are separated in the…

Spectroscopic ellipsometry is used to determine the dielectric function of the superconducting LaFeAsO$_{0.9}$F$_{0.1}$ ($T_c$ = 27 K) and undoped LaFeAsO polycrystalline samples in the wide range 0.01-6.5 eV at temperatures 10 $\leq T…

Measurements of magnetization, specific heat, electrical resistivity, Hall effect, and magnetoresistance on single crystalline samples of LaFeAsO grown in a NaAs flux are reported. While this material is known to be a semimetal, the…

The phonon dispersion was measured at room temperature along (0,0,L) in the tetragonal phase of LaFeAsO using inelastic x-ray scattering. Spin-polarized first-principles calculations imposing various types of antiferromagnetic order are in…

We report a $^{75}$As nuclear magnetic resonance study in LaFeAsO single crystals, which undergoes nematic and antiferromagnetic transitions at $T_\text{nem}\sim 156$ K and $T_N \sim 138$ K, respectively. Below $T_\text{nem}$, the $^{75}$As…

We have measured the temperature dependence of the photoemission and x-ray absorption spectra of La$_{1-x}$Sr$_x$FeO$_3$ (LSFO) epitaxial thin films with $x=0.67$, where charge disproportionation ($3{Fe}^{3.67+}\to 2{Fe}^{3+}+ {Fe}^{5+}$)…

We report infrared spectra of a Na$_{0.5}$CoO$_2$ single crystal which exhibits a sharp metal-insulator transition near 50 K due to the formation of charge ordering. In comparison with x=0.7 and 0.85 compounds, we found that the spectral…

The magnetic, transport and optical properties of EuFe$_2$As$_2$ single crystals have been investigated parallel and perpendicular to the $ab$-plane. The anisotropy $\rho_c/\rho_{ab}\approx 8$ depends only slightly on temperature. In both…

We investigate the temperature dependent optical properties of NaV2O5, in the energy range 4meV-4eV. The symmetry of the system is discussed on the basis of infrared phonon spectra. By analyzing the optically allowed phonons at temperatures…

Epitaxial thin films of LaFeAsO were fabricated on MgO (001) and mixed-perovskite (La, Sr)(Al, Ta)O3 (001) single-crystal substrates by pulsed laser deposition using a Nd:YAG second harmonic source and a 10 at.% F-doped LaFeAsO disk target.…

Magnetic and electronic structures in LaFeAsO in the single-stripe-type antiferromagnetic (AFM) phase are studied using first-principles density-functional calculations including the spin-orbit interaction. We show that the longitudinal…

We report the in-plane optical measurements on Na$_x$CoO$_2$ with 0.18$\leq$x$\leq$0.92. The crystal growth and characterization were described in detail. The spectral weight increases monotonically with decreasing x. For sample with the…

We investigated LaFeAsO single crystals by means of synchrotron M\"ossbauer spectroscopy under pressures up to 7.5 GPa and down to 13 K and provide a microscopic phase diagram. We found a continuous suppression of the magnetic hyperfine…

The existence of orbital-dependent electronic correlations has been recognized as an essential ingredient to describe the physics of iron-based superconductors. NaFeAs, a parent compound of iron based superconductors, exhibits a…

Inelastic neutron scattering was employed to investigate the impact of electronic nematic order on the magnetic spectra of LaFeAsO and Ba(Fe$_{0.953}$Co$_{0.047}$)$_{2}$As$_{2}$. These materials are ideal to study the paramagnetic-nematic…

We perform an in-plane optical spectroscopy measurement on high quality FeSe single crystals grown by a vapor transport technique. Below the structural transition at $T_{\rm s}\sim$90 K, the reflectivity spectrum clearly shows a gradual…

The electronic band structures of the LaOFeP superconductor have been calculated theoretically by the first principles method and measured experimentally by electron energy loss spectroscopy. The calculations indicate that the Fe atom in…

We present the optical properties of \na single crystals, measured over a broad spectral range as a function of temperature ($T$). The capability to cover the energy range from the far-infrared up to the ultraviolet allows us to perform…

We report the experimental results of temperature dependent polarized As K-edge extended x-ray absorption fine structure (EXAFS) of LaFe1-xCoxAsO (x=0.0 and 0.11) single-crystals. By aligning the Fe-As bond direction in the direction of the…

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…