We use molecular dynamics simulation to calculate the thermal conductivities of（5, 5） carbon nanotube superlattices（CNTSLs） and defective carbon nanotubes（DCNTs）, where CNTSLs and DCNTs have the same size. It is...We use molecular dynamics simulation to calculate the thermal conductivities of（5, 5） carbon nanotube superlattices（CNTSLs） and defective carbon nanotubes（DCNTs）, where CNTSLs and DCNTs have the same size. It is found that the thermal conductivity of DCNT is lower than that of CNTSL at the same concentration of Stone–Wales（SW） defects. We perform the analysis of heat current autocorrelation functions and observe the phonon coherent resonance in CNTSLs, but do not observe the same effect in DCNTs. The phonon vibrational eigen-mode analysis reveals that all modes of phonons are strongly localized by SW defects. The degree of localization of CNTSLs is lower than that of DCNTs, because the phonon coherent resonance results in the phonon tunneling effect in the longitudinal phonon mode. The results are helpful in understanding and tuning the thermal conductivity of carbon nanotubes by defect engineering.展开更多
Resonant linear and nonlinear properties in terahertz range of 2D materials graphene and silicene placed into a bias magnetic field are investigated theoretically on the base of the quasi-classical kinetic theory. Whe...Resonant linear and nonlinear properties in terahertz range of 2D materials graphene and silicene placed into a bias magnetic field are investigated theoretically on the base of the quasi-classical kinetic theory. When the electromagnetic frequency is close to the cyclotron one, the linear conductivity increases two orders. Under the resonant frequencies nonlinearity becomes essential at low magnitudes of terahertz electric fields. In absence of a bias magnetic field the nonlinear dependences of the surface electric currents on terahertz electric field are practically the same simulated from kinetics and electron hydrodynamics with nonzero “kinetic” electron effective mass. Graphene possesses higher values of nonlinearity of the resonant conductivity, whereas in absence of a bias magnetic field, the electron nonlinearity is higher in silicene.展开更多
The differential cross section for an electron Raman scattering process in a semiconductor GaAs/AlGaAs double quantum well wire is calculated,and expressions for the electronic states are presented.The system is model...The differential cross section for an electron Raman scattering process in a semiconductor GaAs/AlGaAs double quantum well wire is calculated,and expressions for the electronic states are presented.The system is modeled by considering T = 0 K and also with a single parabolic conduction band,which is split into a subband system due to the confinement.The gain and differential cross-section for an electron Raman scattering process are obtained.In addition,the emission spectra for several scattering configurations are discussed,and interpretations of the singularities found in the spectra are given.The electron Raman scattering studied here can be used to provide direct information about the efficiency of the lasers.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11404278 and 11275163)the Science Foundation of Hunan Province,China(Grant No.2016JJ2131)
文摘We use molecular dynamics simulation to calculate the thermal conductivities of（5, 5） carbon nanotube superlattices（CNTSLs） and defective carbon nanotubes（DCNTs）, where CNTSLs and DCNTs have the same size. It is found that the thermal conductivity of DCNT is lower than that of CNTSL at the same concentration of Stone–Wales（SW） defects. We perform the analysis of heat current autocorrelation functions and observe the phonon coherent resonance in CNTSLs, but do not observe the same effect in DCNTs. The phonon vibrational eigen-mode analysis reveals that all modes of phonons are strongly localized by SW defects. The degree of localization of CNTSLs is lower than that of DCNTs, because the phonon coherent resonance results in the phonon tunneling effect in the longitudinal phonon mode. The results are helpful in understanding and tuning the thermal conductivity of carbon nanotubes by defect engineering.
文摘Resonant linear and nonlinear properties in terahertz range of 2D materials graphene and silicene placed into a bias magnetic field are investigated theoretically on the base of the quasi-classical kinetic theory. When the electromagnetic frequency is close to the cyclotron one, the linear conductivity increases two orders. Under the resonant frequencies nonlinearity becomes essential at low magnitudes of terahertz electric fields. In absence of a bias magnetic field the nonlinear dependences of the surface electric currents on terahertz electric field are practically the same simulated from kinetics and electron hydrodynamics with nonzero “kinetic” electron effective mass. Graphene possesses higher values of nonlinearity of the resonant conductivity, whereas in absence of a bias magnetic field, the electron nonlinearity is higher in silicene.
文摘The differential cross section for an electron Raman scattering process in a semiconductor GaAs/AlGaAs double quantum well wire is calculated,and expressions for the electronic states are presented.The system is modeled by considering T = 0 K and also with a single parabolic conduction band,which is split into a subband system due to the confinement.The gain and differential cross-section for an electron Raman scattering process are obtained.In addition,the emission spectra for several scattering configurations are discussed,and interpretations of the singularities found in the spectra are given.The electron Raman scattering studied here can be used to provide direct information about the efficiency of the lasers.
