共查询到19条相似文献,搜索用时 46 毫秒
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在经典的物理学理论中,声子广泛地被认为是线极化的、不具有角动量的.最近的理论研究发现,在具有自旋声子相互作用的磁性体系(时间反演对称性破缺)中,声子可以携带非零的角动量,在零温时声子除了具有零点能以外还带有零点角动量;非零的声子角动量将会修正通过爱因斯坦-德哈斯效应测量的回磁比.在非磁性材料中,总的声子角动量为零,但是在空间反演对称性破缺的六角晶格体系中,其倒格子空间的高对称点上声子具有角动量,并具有确定的手性;三重旋转对称操作给予声子量子化的赝角动量,赝角动量的守恒将决定电子谷间散射的选择定则;此外还理论预测了谷声子霍尔效应. 相似文献
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应用全势线性响应线性糕模轨道(FP-LR-LMTO)方法对MgcM3镁位进行钠掺杂的虚原子近似,计算晶格振动的动力学矩阵,得到Mg1-xNaxCNi3(x=0,0.06)的声子谱.计算结果表明MgCNi3声子谱中最低声学支沿F-M方向有接近一半距离的不稳定声子模存在,不稳定声子模都包括存原胞内x-y平面上两个相邻Ni原子沿着与C-Ni键垂直的方向上,向着镍八面体间隙区的垂直运动x为0.06的掺杂,使得布里渊区沿三个主要高对称性方向(Г-x、Г-M、Г-R)虚频范围扩大,容易使MgCNi3结构不稳定而产生结构相变. 相似文献
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声子散射对碳纳米管场效应管(carbon nanotube field effect transistor, CNTFET)的特性有着不可忽略的影响. 传统研究方法基于弹道输运模型来分析发生声子散射时各参数对器件特性的影响, 进而建立CNTFET声子散射模型.为了降低模型复杂度, 提高仿真计算的速度, 本文深入研究了CNTFET的声子散射影响, 对手性、温度和能量三个参数的变化进行了仿真, 分析了参数对器件特性的影响. 采用线性近似拟合的方式建立了一种新的CNTFET声子散射模型.通过分析散射下电流的变化, 验证了该模型的正确性和有效性.与半经典散射模型相比, 该模型由于不需要进行积分计算, 计算过程较为简单, 降低了运算量.
关键词:
碳纳米管场效应管
声子散射模型
线性近似拟合 相似文献
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基于线性波尔兹曼输运方程和碳纳米管的色散关系,本文研究了声子散射的Umklapp和Normal过程同时存在时单壁碳纳米管的晶格热导率,以及温度、管长和管径对它的影响.结果表明:N过程的影响在高温不能忽略;对(10,0)管而言,在低温下其导热率随温度升高迅速增大,在90 K附近达到最大值,然后逐渐开始下降;热导率与管长L的关系是κ∝ L1/2;在相同管长和温度下,热导率随管径的减小而增大. 相似文献
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D.V. Pozdnyakov V.O. Galenchik F.F. Komarov V.M. Borzdov 《Physica E: Low-dimensional Systems and Nanostructures》2006,33(2):336-342
The rates of electron scattering via phonons in the armchair single-wall carbon nanotubes were calculated by using the improved scattering theory within the tight-binding approximation. Therefore, the problem connected with the discrepancy of the scattering rates calculated in the framework of the classical scattering theory and ones predicted by experimental data was clarified. Then these results were used for the solving of the kinetic Boltzmann equation to describe electron transport properties of the nanotubes. The equation was solved numerically by using both the finite difference approach and the Monte Carlo simulation procedure. 相似文献
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碳纳米管的表面修饰及FTIR,Raman和XPS光谱表征 总被引:1,自引:4,他引:1
用红外、拉曼光谱、X射线光电子能谱(XPS)研究了水热条件下碳纳米管在不同氧化剂中的表面修饰过程。结果表明水热条件下可以成功地实现碳纳米管的表面修饰,而且,通过控制反应条件可以改变反应产物中官能团的种类和数量。 相似文献
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Manashi Roy 《Pramana》1974,2(5):273-281
The phonon drag resistivity for potassium is calculated by solving the Boltzman equations for both the electrons and phonons
as opposed to the conventional method of Ziman where the phonon equation is not considered. By an application of the Schwartz
inequality we can show that the drag resistivity in the present formalism is larger than that obtained by the conventional
method. We substantiate this result by numerical calculation for potassium at very low temperatures, using a realistic phonon
spectrum obtained from inelastic neutron scattering data.
Parts of this paper were presented as partial fulfilment for a Ph.D. degree at Cornell University. The work was partially
supported by CSIR funding. 相似文献
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Wolfgang Frick Dieter Waldmann Wolfgang Eisenmenger 《Applied Physics A: Materials Science & Processing》1975,8(2):163-171
Thin metallic films evaporated on an Al2O3-single crystal and cooled to liquid helium temperatures are heated by short electric current pulses. The high frequency part
of the emitted phonons is detected by calibrated superconductive tunneling junctions on the opposite surface of the substrate.
The observed phonon detector signal amplitude is compared with theoretical models taking account of the boundary conditions
for elastic waves in the film. It is found that the phonon spectrum emitted perpendicularly to the substrate-film boundary
depends strongly on the thickness of the heater film. 相似文献
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Recently Animalu has developed a model potential approach to study the electronic properties of transition metals. We have
applied the transition metal model potential (TMMP) of Animalu in the local approximation to derive the phonon dispersion
curves of Zn and Cd alongΓA,ΓM andΓKM symmetry directions. Our results differ widely from the experimental data. Further we have added the non-local contribution
to the dynamical matrix following the scheme of Eschrig and Wonn and found the resuits comparable to the measured ones. 相似文献
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在传统的热化学气相沉积(CVD)的基础上,引入针尖电场,开展了电场对碳纳米管阵列准直性改善的研究。利用扫描电子显微镜(SEM)和Raman光谱两种表征手段,研究了加电场与不加电场两种情况下得到的碳纳米管(CNT)阵列的准直性,证明了电场对碳纳米管阵列准直生长的有效性。文章还对电场诱导碳纳米管阵列准直生长的机理进行了初步的探讨,认为电场使碳纳米管极化是CNT阵列准直生长的主要原因。 相似文献
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The properties of carbon nanotube as optical antennae have been studied. The equation of current distribution on a single
antenna has been obtained by using conventional transmission line theories. The re-radiation lobe pattern of a single antenna
and an antenna arrays have been gained by computer simulation. 相似文献