We consider the existence of plasmons in a nonequilibrium situation where electrons from the valence band of graphene are pumped to states in the Brillouin zone around the M point by a high intensity UV electromagnetic field. The resulting out-of-equilibrium electron gas is later probed by a weak electromagnetic field of different frequency. We show that the optical properties of the system and...

The lattice instabilities of perovskite structure oxides are responsible for many of their interesting properties, such as temperature-dependent ferroelectric phase transitions. First-principles calculations using linear response theory provide an accurate means to determine the lattice dynamics throughout the entire Brillouin zone (BZ). Using the LAPW linear response method [1], we have previo...

Magnon linewidth of La1.2Sr1.8Mn2O7 near the Brillouin zone boundary is investigated from both theoretical and experimental points of view. Abrupt magnon broadening is ascribed to a strong magnon-phonon coupling. Magnon broadening observed in cubic perovskite manganites is also discussed.

The electronic structure of the diamond C(lOO)-(2x1)/(%2) has been investigated by means of angle-resolved photoelectron spectroscopy for the first time. A surfacerelated shift has been observed in the C 1s core level spectrum. The surface-state band dispersion was measured along the symmetry axis F-J’ in the surface Brillouin zone. For k,, = 0, there is a-very pronounced surface state 1.5 eV b...

We study the one-dimensional Holstein model of spinless fermions interacting with dispersionless phonons by using a recently developed projector-based renormalization method (PRM). At half-filling the system shows a metal-insulator transition to a Peierls distorted state at a critical electron-phonon coupling where both phases are described within the same theoretical framework. The transition ...

Based on first-principles and tight-binding calculations, we report that the topological edge states of zigzag Bi(111) nanoribbon can be significantly tuned by H edge adsorption. The Fermi velocity is increased by 1 order of magnitude, as the Dirac point is moved from the Brillouin zone boundary to the Brillouin zone center, and the real-space distribution of Dirac states are made twice more de...