Related papers: Vibrational anomalies in AFe$_\mathbf{2}$As$_\math…
The superconducting state of an optimally doped single crystal of Ba(Fe$_{0.93}$Co$_{0.07}$)$_2$As$_2$ was investigated by $^{75}$As NMR in high magnetic fields from 6.4 T to 28 T. It was found that the Knight shift is least affected by…
With infrared spectroscopy we investigated the spin-reorientation transition from an orthorhombic antiferromagnetic (o-AF) to a tetragonal AF (t-AF) phase and the reentrance of the o-AF phase in the superconducting state of underdoped Ba$…
We use neutron scattering to determine spin excitations in single crystals of nonsuperconducting Li1-xFeAs throughout the Brillouin zone. Although angle resolved photoemission experiments and local density approximation calculations suggest…
75As NMR and susceptiblity were measured in a Ba(Fe1-xCox)2As2 single crystal for x=6%. Nuclear Magnetic Resonance (NMR) spectra and relaxation rates allow to show that all Fe sites experience an incommensurate magnetic ordering below…
The magnetic, transport and optical properties of EuFe$_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…
Optical spectroscopy on single crystals of the new iron arsenide superconductor Ba{0.55}K{0.45}Fe2As2 shows that the infrared spectrum consists of two major components: a strong metallic Drude band and a well separated mid infrared…
We report results of electron spin resonance (ESR) measurements in single crystals of EuSn$_2$As$_2$. In the temperature range of antiferromagnetic (AFM) ordering of Eu atoms, $T \leq T_N\approx 24$\,K, the ESR signal splits into two…
Two magnetic transitions are observed in the magneto-superconducting RuEu2-xCexSr2Cu2O10 (Ru-1222), at TM 160 K and TM2~80 K. Below TM2 the Ru moments are weak-ferromagnetically ordered and wide ferromagnetic hysteresis loops are observed,…
The motivation of this work is our recent observation of the robustness of superconductivity in a High-entropy (HE) superconductor Ag0.2In0.2Sn0.2Pb0.2Bi0.2Te (CsCl-type) to external pressure. The superconducting transition temperature (Tc)…
We report $^{75}$As nuclear magnetic resonance measurements on single crystals of RbFe$_{2}$As$_{2}$ and CsFe$_{2}$As$_{2}$. Taking previously reported results for KFe$_{2}$As$_{2}$ into account, we find that the anisotropic electronic…
In this work, we report the broad-band ferromagnetic resonance spectroscopy of EuSn$_2$As$_2$ single crystals at different temperatures in combination with magnetization measurements and structural characterization. We observe conventional…
Dynamical properties of the lattice structure was studied by optical spectroscopy in ACr2O4 chromium spinel oxide magnetic semiconductors over a broad temperature region of T=10-335K. The systematic change of the A-site ions (A=Mn, Fe, Co,…
$^{75}$As and $^{139}$La NMR results of LaFeAs(O$_{1-x}$F$_x$) ($x$=0, 0.025, and 0.04) were reported. Upon F-doping, the tetragonal-to-orthorhombic structural phase transition temperature $T_S$, antiferromagnetic transition temperature…
Inelastic scattering of visible light (Raman effect) offers a window into properties of correlated metals such as spin, electron and lattice dynamics as well as their mutual interactions. In this review we focus on electronic and spin…
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…
Analysis of the a-b plane optical conductivity $\sigma_{ab}$ for both twinned and untwinned YBa$_{2}$Cu$_{3}$O$_{7-\delta}$ as a function of temperature and doping shows that below a well defined temperature T*, a dip in the spectrum…
We consider the excitation of radial and non-radial oscillations in low-mass B stars by the iron-bump opacity mechanism. The results are significant for the interpretation of pulsations in subdwarf B stars, helium-rich subdwarfs and extreme…
Tungsten ditelluride (WTe2) is a layered material that exhibits excellent magnetoresistance and thermoelectric behaviors, which are deeply related with its distorted orthorhombic phase that may critically affect the lattice dynamics. Here,…
To elucidate the origin of nematic order in Fe-based superconductors, we report a Raman scattering study of lattice dynamics, which quantify the extent of $C_4$-symmetry breaking, in BaFe$_2$As$_2$ and FeSe. FeSe possesses a nematic…
A comparative analysis of the properties of FeSe${}_{1-x}$Te${}_{x}$ crystals in the range of x values of about 0.4 and pure FeSe crystals is presented. We found that the anomaly in R (T) at the structural transition for the former differs…