Conductivity Tensor in Cylindrical Quantum Wire with Parabolic Potential for the Case of Electron-Acoustic Phonon Scattering

Conductivity tensor is an important concept in materials, this work studies conductivity tensors in cylindrical quantum wires with parabolic potential in the presence of two external fields, a linearly polarized electromagnetic wave, and a laser field. This work is also only considered for the case of electron-acoustic phonon scattering. Research results are obtained by using quantum kinetic equations for the carrier system in a quantum wire. The conductivity tensor is calculated by solving the quantum kinetic equation of the system, which is a function of the external field frequency, the external field amplitude, the temperature of the helium, and parameters specific to the quantum wire. Results will also be examined and plotted for quantum wire GaAs / GaAsAl.

One-dimensional cylindrical quantum wire: The theoretical study of photo-stimulated Ettingshausen effect

Based on the quantum kinetic equation (QKE) for electron, we have theoretically studied the theory of photo-stimulated Ettingshausen effect in a one-dimensional cylindrical quantum wire (CQW). The strong electromagnetic wave (EMW) [Formula: see text] plays a role as photo-stimulation source. We obtain the analytic expressions for the kinetic tensors [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text] and the Ettingshausen coefficient (EC) in the CQW with the dependence on the amplitude and the energy of EMW, the CQW radius, the magnetic field and the temperature for two cases: optical phonon and acoustic phonon. The results are numerically evaluated and graphed for GaAs/AlGaAs CQW model. It is shown that we observe the cyclotron resonance and magneto-phonon resonance effect while surveying EC in terms of magnetic field (with and without EMW) and EMW energy, considered the electron-optical phonon scattering. In case of electron-acoustic phonon scattering, the oscillation of EC is obtained with the transition between low Landau levels (LLs). We also clarify the impact of quantum size effect (QSE) on EC by surveying the influence of EC on the radius of CQW.

Canalization acoustic phonon polaritons in metal-MoO3-metal sandwiched structures for nano-light guiding and manipulation

We theoretically propose and study in-plane anisotropic acoustic phonon polaritons (APhPs) based on a layered structure consisting of a monolayer (or few layers) α-phase molybdenum trioxide (α-MoO3) sandwiched between two metal layers. We find that the APhPs in the proposed sandwiched structures are a canalization (highly directional) electromagnetic mode propagating along with the layers and at the same time exhibit extreme electromagnetic-field confinement surpassing any other type of phonon-polariton modes. When a double layer of α-MoO3 is sandwiched by two Au layers, twisting the two α-MoO3 layers can adjust the interlayer polaritonic coupling and thus manipulate the in-plane propagation of the highly confined APhPs. Our results illustrate that the metal-MoO3-metal sandwiched structures are a promising platform for light guiding and manipulation at ultimate scale.

Thermal Conductivity of BAs under Pressure

Boron arsenide (BAs) is an ultrahigh-thermal-conductivity material with special phonon-phonon scattering behaviors. At ambient pressure, the bunching of acoustic phonon branches in BAs is believed to result in a small phase space for three-phonon scattering. Density functional theory predicts that this acoustic phonon bunching effect is sensitive to pressure and leads to an unusual pressure dependence of thermal conductivity. To explore this physics, we measure the thermal conductivity of BAs from 0 to 25 GPa using time-domain thermoreflectance in a diamond anvil cell. We characterized two BAs samples with ambient thermal conductivities of 350 and 480 W m-1 K-1. Our experiments show that the thermal conductivity of both samples depends weakly on pressure from 0 to 25 GPa. We attribute the weak pressure dependence of the thermal conductivity of BAs to the weak pressure dependence of total phonon-phonon scattering rates. Our experimental results are consistent with DFT predictions that three-phonon scattering rates increase from 0 to 25 GPa, while four-phonon scattering rates decrease.

Acoustoelectric current in graphene nanoribbon due to Landau damping

We perform self-consistent analysis of the Boltzmann transport equation for momentum and energy in the hypersound regime i.e., $$ql \gg 1$$ q l ≫ 1 ($$q$$ q is the acoustic wavenumber and l is the mean free path). We investigate the Landau damping of acoustic phonons ($$LDOAP$$ LDOAP ) in graphene nanoribbons, which leads to acoustoelectric current generation. Under a non-quantized field with drift velocity, we observed an acoustic phonon energy quantization that depends on the energy gap, the width, and the sub-index of the material. An effect similar to Cerenkov emission was observed, where the electron absorbed the confined acoustic phonon energy, causing the generation of acoustoelectric current in the graphene nanoribbon. A qualitative analysis of the dependence of the absorption coefficient and the acoustoelectric current on the phonon frequency is in agreement with experimental reports. We observed a shift in the peaks when the energy gap and the drift velocity were varied. Most importantly, a transparency window appears when the absorption coefficient is zero, making graphene nanoribbons a potential candidate for use as an acoustic wave filter with applications in tunable gate-controlled quantum information devices and phonon spectrometers.

The Influece of The Laser on Acoustic Phonon Amplification in Parabolic Potential Well

We present a theoretical study of the kinetic equation for acoustic phonons in semiconductor quantum well with parabolic potential well under intense laser field. Using this method, we find the expression for the phonon rate coefficient for the general case, the condition of the acoustic phonon rate and the influence of the parameters of laser on this rate coefficient. We numerically calculate the rate of acoustic phonon excitation by the absorption of laser field energy at different temperature.