相关论文: Amplification of acoustic phonons in superlattice

Hypersound Absorption of acoustic phonons having $ql>>1$ in a degenerate Carbon Nanotube (CNT) with linear energy dispersion near the Fermi level was theoretically studied. The general expression for the absorption coefficient ($\Gamma$)…

Hypersound amplification/absorption of acoustic phonons in Graphene with degenerate energy dispersion $\varepsilon(p)$ near the Fermi level was theoretically studied. For $k_{\beta}T << 1$ and $ql >> 1$, the dependence of the absorption…

In graphene devices, the electronic drift velocity can easily exceed the speed of sound in the material at moderate current biases. Under this condition, the electronic system can efficiently amplify acoustic phonons, leading to the…

We provide a quantum mechanical description of phonon amplification in a heterostructure consisting of a two-dimensional electron gas (2DEG) stacked on top of a piezoelectric material. An applied drift voltage effectively creates a…

We analyze the Cerenkov emission of high-frequency confined acoustic phonons by drifting electrons in a quantum well. We find that the electron drift can cause strong phonon amplification (generation). A general formula for the gain…

Based on the quantum transport equation for the electron-phonon system, the absorption coefficient of sound (acoustic phonons) by absorption of a laser radiation in quantum wires with parabolic potential is calculated for the case of…

Intersubband transitions in a superlattice under homogeneous electric field is studied within the tight-binding approximation. Since the levels are equi-populated, the non-zero response appears beyond the Born approximation. Calculations…

Amplification of light through stimulated emission or nonlinear optical interactions has had a transformative impact on modern science and technology. The amplification of other bosonic excitations, like phonons in solids, is likely to open…

Quantum coherent coupling between a zone-center phonon and two acoustic phonons was observed in two GaAs/AlAs superlattices (8 nm/8 nm and 5.4 nm/5.4 nm) at ambient temperature. Using degenerate coherent phonon spectroscopy, a multi-cycle…

Acoustic wave propagation in bulk GaN Semiconductor in the presence of a slowly changing a.c electric field and a constant electric field has been studied. Analytical expression for the attenuation (amplification) coefficient has been…

We consider a high-frequency response of electrons in a single miniband of superlattice subject to dc and ac electric fields. Action of ac electric field causes oscillations of electron's effective mass in miniband, which result in a…

Based on the quantum transport equation for the electron-phonon system, the absorption coefficient of sound (acoustic phonons) by absorption of laser radiation in cylindrical quantum wires is calculated for the case of monophoton absorption…

Amplification of acoustic phonons due to an external temperature gredient ($\nabla T$) in Graphene was studied theoretically. The threshold temperature gradient $(\nabla T)_0^{g}$ at which absorption switches over to amplification in…

Interactions with electronic excitations can soften and/or broaden phonons. They are greatly amplified at wavevectors Q+- that connect parallel (nested) sheets of the Fermi surface. In such a case, called a Kohn anomaly, the phonon…

We present a detailed study of a phonon-assisted incoherent excitation mechanism of single quantum dots. A spectrally-detuned laser couples to a quantum dot transition by mediation of acoustic phonons, whereby excitation efficiencies up to…

We have investigated the dynamical properties of coherent phonons generated in antimony under high density photo excitation. Precise measurements and extended analysis of coherent phonon oscillations provide new insights into the process of…

The lattice dynamics and the effect of pressure on superconducting LiFeAs in both nonmagnetic (NM) and striped antiferromagnetic (SAF) phases are investigated using the plane-wave pseudopotential, density-functional-based method. While the…

The existence of an acoustic plasmon in extrinsic (doped or gated) monolayer graphene was found recently in an {\it ab initio} calculation with the frozen lattice [M. Pisarra {\it et al.}, arXiv:1306.6273, 2013]. By the {\em fully dynamic}…

Radio-frequency compressed ultrafast electron diffraction has been used to probe the coherent and incoherent coupling of impulsive electronic excitation at 1.55 eV (800 nm) to optical and acoustic phonon modes directly from the perspective…

We study the principal aspects of the interaction between acoustic phonons and two-dimensional electrons in quantizing magnetic fields corresponding to even denominator fractions. Using the composite fermion approach we derive the vertex of…