Related papers: Phonon anomalies with doping in superconducting ox…
We report an anomalous local structural response in the CuO2 planes associated with the appearance of charge inhomogeneities at low temperature in underdoped but superconducting La2-x(Sr,Ba)xCuO4. We used pair distribution function analysis…
Phononic and magnetic Raman scattering are studied in La$_{2-x-y}$Nd$_{y}$Sr$_{x}$CuO$_{4}$ with three doping concentrations: x ~ 1/8, y = 0; x ~ 1/8, y = 0.4; and x = 0.01, y = 0. We observe strong disorder in the tilt pattern of the…
The parent compounds of the copper oxide high-Tc superconductors are unusual insulators. Superconductivity arises when they are properly doped away from stoichiometry1. In Bi2Sr2CaCu2O8+x, superconductivity results from doping with excess…
Using the large-$N$ limit of the $t$-$J$ model and allowing also for phonons and the electron-phonon interaction we study the isotope effect $\alpha$ for coupling constants appropriate for YBCO. We find that $\alpha$ has a minimum at…
We have studied the lattice dynamics, electron-phonon coupling, and superconducting properties of $\alpha$-MoB$_2$, as a function of applied pressure, within the framework of density functional perturbation theory using a mixed-basis…
Monoclinic crystal structure of the undoped BaBiO3 can be described as a cubic perovskite distorted by a frozen breathing and tilting phonon modes of BiO6 octahedra. The phonon mode softening is experimentally observed [M. Braden et al.,…
We report detailed measurements of composition as well as temperature dependence of the phonon density-of-states in a new series of FeAs compounds with composition CaFe1\_{1-x}Co\_{x}AsF (x = 0, 0.06, 0.12). The composition as well as…
We report a persistent low-energy phonon broadening around $q_{B} \sim 0.28$ r.l.u. along the Cu-O bond direction in the high-$T_c$ cuprate Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ (Bi-2212). We show that such broadening exists both inside and…
We present a comparative experimental and theoretical investigation of the two--dimensional charge-transfer gap in the strongly correlated material Sr$_2$CuO$_2$Cl$_2$. We observe an Urbach behaviour in the absorption profile over a…
Phonon or electron mediated weak BCS attraction is enough to have high critical temperature if a van Hove anomaly is at work. This could apply to electron doped compounds and also to compounds with CuO$_2$ planes overdoped in holes, where…
Charge density waves (CDWs) are ubiquitous in under-doped cuprate superconductors. As a modulation of the valence electron density, CDWs in hole-doped cuprates possess both Cu-3d and O-2p orbital character owing to the strong hybridization…
The quasiparticle relaxation dynamics of the iron-based superconductor CsCa$_2$Fe$_4$As$_4$F$_2$ ($T_c$ $\sim$ 29 K) were investigated using ultrafast optical spectroscopy. A pseudogap ($\Delta_{PG}$ $\approx$ 3.3 meV) was observed to open…
We report results of inelastic neutron scattering measurements of phonon dispersions on a detwinned sample of YBaCu3O7 and compare them with model calculations. Plane oxygen bond stretching phonon branches disperse steeply downwards from…
By means of the first-principles density-functional theory calculation and Wannier interpolation, electron-phonon coupling and superconductivity are systematically explored for boron-doped LiBC (i.e. LiB$_{1+x}$C$_{1-x}$), with $x$ between…
The magnon dispersion of Ca$_2$RuO$_4$ has been studied by polarized and unpolarized neutron scattering experiments on crystals containing 0, 1 and 10 % of Ti. The entire dispersion of transverse magnons can be well described by a…
We employ an optical pump-probe technique to study coherent phonon oscillations in Ca$_2$RuO$_4$. We find that oscillation-amplitude of an $A_g$ symmetric phonon mode is strongly suppressed at 260 K, a putative transition point of orbital…
We report measurements of the phonon dispersion relations in non-superconducting, oxygen-deficient PrBa2Cu3O6+x (x ~ 0.2) by inelastic neutron scattering. The data are compared with a model of the lattice dynamics based on a common…
We report the in-plane optical measurements on Na$_x$CoO$_2$ with 0.18$\leq$x$\leq$0.92. The crystal growth and characterization were described in detail. The spectral weight increases monotonically with decreasing x. For sample with the…
Temperature-dependent polarized Raman spectra of electron-doped superconducting Pr$_x$Ca$_{1-x}$Fe$_2$As$_2$ ($x \approx 0.12$) single crystals are reported. All four allowed by symmetry even-parity phonons are identified. Phonon mode of…
We report measurements of phonon dispersion in CaC$_6$ using inelastic X-ray and neutron scattering. We find good overall agreement, particularly in the 50 meV energy region, between experimental data and first-principles…