Trilayer graphene in both ABA (Bernal) and ABC (rhombohedral) stacking sequences is shown to exhibit intense infrared absorption from in-plane optical phonons. The phonon feature, lying at ~1580 cm(-1), changes strongly with electrostatic gating. For ABC-stacked graphene trilayers, we observed a large enhancement in phonon absorption amplitude, as well as softening of the phonon mode, as the Fe...

We have observed coherent optical and acoustic phonon generation, which are strongly coupled to the charge-ordering sCOd transition in La1−xCaxMnO3 sx=0.5, 0.58d using femtosecond optical pump-probe spectroscopy. Coherent optical phonons, observed at low temperatures, disappear above the charge-ordering temperature TCO, while coherent acoustic phonons display the opposite behavior, disappearing...

We study the vibrational stability of model 2D solids with surfaces when large strains are present. For a fiber under compression, the phonon analysis correctly predicts the behavior of the buckling instability. For half-space under tension and compression, we find that (a) instabilities of the surface phonons, which are localized near the surface, almost always occur before bulk phonon instabi...

Existence of sub-thermal collective excitations in proteins is of great interest due to its possible close coupling with the onset of their biological functions. We use high-energy resolution inelastic X-ray scattering to directly measure phonon dispersion relations and their damping in two hydrated proteins, a-chymotrypsinogen A and casein, differing in their secondary and tertiary structures....

In this paper we investigate the electron-phonon contribution to the resistivity of suspended single-layer graphene. In-plane as well as flexural phonons are addressed in different temperature regimes. We focus on the intrinsic electron-phonon coupling due to the interaction of electrons with elastic deformations in the graphene membrane. The competition between screened deformation potential v...

To minimize the lattice thermal conductivity in thermoelectrics, strategies typically focus on the scattering of low-frequency phonons by interfaces and high-frequency phonons by point defects. In addition, scattering of mid-frequency phonons by dense dislocations, localized at the grain boundaries, has been shown to reduce the lattice thermal conductivity and improve the thermoelectric perform...

We present Raman spectra of InP measured under nonresonant conditions revealing multiphonon processes up to fifth order. Using an incident photon energy in the absorption region of the compound but far from any of its interband transitions, nonresonant multiphonon processes of order higher than two, which have not been reported so far in a zinc-blende-type semiconductor, have been observed in i...