Using high-resolution angle-resolved photoemission spectroscopy we have studied the momentum and photon energy dependence of the anomalous high-energy dispersion, termed waterfalls, between the Fermi level and 1 eV binding energy in several high-T_{c} superconductors. We observe strong changes of the dispersion between different Brillouin zones and a strong dependence on the photon energy aroun...

We demonstrate that both the linear (diffraction) and the nonlinear dynamics of two-dimensional waveguide arrays are considerably more complex and versatile than their one-dimensional counterparts. The discrete diffraction properties of these arrays can be effectively altered, depending on the propagation Bloch k-vector within the first Brillouin zone of the lattice. In general, this diffractio...

The Fourier spectra of longitudinal and transverse waves corresponding to random particle motion were measured in a two-dimensional plasma crystal. The crystal was composed of negatively charged microspheres immersed in a plasma at a low gas pressure. The phonons were found to obey a dispersion relation that assumes a Yukawa interparticle potential. The crystal was in a nonthermal equilibrium, ...

When vortices move in a type-II superconductor under the action of an electric current, they interact with the crystal lattice generating acoustic waves. This results in a radiation-friction component to the vortex dissipation, which peaks at values of vortex velocity where there are phonons in the Brillouin zone of the crystal with matching phase and group velocities ~the van Hove condition!. ...

We present analytic expressions for the single particle excitation energies of the 8 quasi–particles in the lattice E8 Ising model and demonstrate that all excitations have an extended Brillouin zone which, depending on the excitation, ranges from 0 < P < 4π to 0 < P < 12π. These are compared with exact diagonalizations for systems through size 10 and with the E8 fermionic representations of th...

A class of sum rules for inelastic light scattering is developed. We show that the first moment of the nonresonant response provides information about the potential energy in strongly correlated systems. The polarization dependence of the sum rules provides information about the electronic excitations in different regions of the Brillouin zone. We determine the sum rule for the Falicov-Kimball ...

We report on the first experimental observation of bright matter wave solitons for 87Rb atoms with repulsive atom-atom interaction. This counterintuitive situation arises inside a weak periodic potential, where anomalous dispersion can be realized at the Brillouin zone boundary. If the coherent atomic wave packet is prepared at the corresponding band edge, a bright soliton is formed inside the ...

The realm of high energy, large wave vector spin waves in ultrathin films and at surfaces is unexplored because a suitable method was not available up to now. We present experimental data for an 8 ML thick Co film deposited on Cu(001) which show that spin-polarized electron energy loss spectroscopy can be used to measure spin-wave dispersion curves of ultrathin ferromagnetic films up to the sur...

The paper describes an efficient method of calculating densities of states g(v) in cubic crystals. The irreducible part of the Brillouin zone is divided into a finite number of cells. In every cell, the constant energy surface is approximated by a set of parallel planes which allows for analytic calculation of g(v). (The SCIx indicates that this paper has been cited in over 440 publications sin...

We review the optical phonon dispersions of graphene. In particular, we focus on the presence of two Kohn anomalies in the highest optical phonon branch at the Γ and K points of the Brillouin zone. We then show how graphene can be used as a model for the calculation of phonons in carbon nanotubes. Finally, we present the beyond Born-Oppenheimer corrections to their phonon dispersions. These are...