相关论文: Correlation effects and phonon modes softening wit…

We have observed a softening of phonons and a structural phase transition in a superconducting Ba0.59K0.41BiO3 (Tc = 31 K) single crystal using elastic and inelastic neutron scattering measurements. The soft phonon occurs for the [111]…

We report density functional calculations based on local density approximation (LDA) of the properties of doped barium bismuthates. Using linear-response approach developed in the framework of the linear muffin-tin-orbital method the phonon…

In the present study, we investigate the thermodynamic properties of the Ba$_{x}$K$_{1-x}$BiO$_{3}$ (BKBO) superconductor in the under- ($x=0.5$) and over-doped ($x=0.7$) regime, within the framework of the Migdal-Eliashberg formalism. The…

Several decades after the discovery of superconductivity in bismuthates, the strength of their electron-phonon coupling and its evolution with doping remain puzzling. To clarify these issues, polycrystalline hole-doped…

The structure of BaMg1/3Ta2/3O3 (BMT) has been studied using X-ray scattering. The phonons have been measured and the results are similar to those of other materials with the perovskite structure such as PbMg1/3Nb2/3O3 (PMN). The acoustic…

We use first-principles methods to study doped strong ferroelectrics (taking BaTiO$_3$ as a prototype). Here we find a strong coupling between itinerant electrons and soft polar phonons in doped BaTiO$_3$, contrary to Anderson/Blount's…

We report the results of the investigation of bulk and surface acoustic phonons in the undoped and boron-doped single-crystal diamond films using the Brillouin-Mandelstam light scattering spectroscopy. The evolution of the optical phonons…

Bulk n-type SrTiO3 (STO) has long been known to possess a superconducting ground state at an exceptionally dilute carrier density. This has raised questions about the applicability of the BCS-Eliashberg paradigm with its underlying…

Barium zirconate BaZrO3 is one of few perovskites that is claimed to retain an average cubic structure down to 0K at ambient pressure, while being energetically very close to a tetragonal phase obtained by condensation of a soft phonon mode…

We observe strong softening of optical phonon modes in superconducting (Tc = 4.2 K) boron doped diamond near the Brillouin zone center using inelastic x-ray scattering from a CVD-grown highly oriented sample. The magnitude of the softening,…

The lattice dynamics of Ba1-xKxFe2As2 (x = 0.00, 0.27) have been studied by inelastic X-ray scattering measurement at room temperature. K doping induces the softening and broadening of phonon modes in the energy range E = 10-15 meV.…

Multiferroics possess two or more switchable states such as polarization, magnetization, etc. Phonon excitations in multiferroic phase are strongly modified by magnetoelectric coupling, spin-phonon coupling, and anharmonic phonon-phonon…

The dispersion of phonons in Ba1-xKxBiO3 along the (3+q, 0, 0) direction in reciprocal space was determined for x=0, 0.30, 0.37, 0.52 using high-resolution inelastic X-ray scattering. The observed phonon energies near \Gamma were in good…

Motivated by the recent experimental discovery of strongly surface-plane-dependent superconductivity at surfaces of KTaO$_3$ single crystals, we calculate the electron-phonon coupling strength, $\lambda$, of doped KTaO$_3$ along the…

Magnetic measurements have been carried out in the superconducting and normal states of the optimally doped nonmagnetic bismuthate superconductor Ba0.63K0.37BiO3. The magnetic data along with previous muSR, resistivity, and tunneling data…

BaBiO3 is a material where formally Bi4+ ions with the half-filled 6s-states form the alternating set of Bi3+ and Bi5+ ions resulting in a charge ordered insulator. The charge ordering is accompanied by the breathing distortion of the BiO6…

Phonon frequencies at {\Gamma},X,M,R-points of Brilloin zone in cubic phase of Ba(Ti,Zr,Hf)O3 were first time calculated by frozen phonon method using density functional theory (DFT) with hybrid exchange correlation functional PBE0. The…

Density functional perturbation theory calculations of alpha-quartz using extended norm conserving pseudopotentials have been used to study the elastic properties and phonon dispersion relations along various high symmetry directions as a…

Barium zirconate (BaZrO$_3$) is one of the very few perovskites that is claimed to retain an average cubic structure down to \SI{0}{\K}, while being energetically very close to an antiferrodistortive phase obtained by condensation of a soft…

We report a direct observation of a sharp Kohn-like anomaly in the doubly degenerate copper-oxygen bond-stretching phonon mode occurring at $\mathbf{q}\mathrm{=(0.3, 0,0)}$ in La$_{2-x}$Ba$_x$CuO$_{4+\delta}$ with $\mathrm{x=0.14\pm0.01}$,…