Theoretical study on phonons in nanowire superlattices

纳米线超晶格中声子的理论研究

• 批准号: 17510093
• 负责人: MIZUNO Seiji
• 金额: $ 1.52万
• 依托单位: Hokkaido University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2005
• 资助国家: 日本
• 起止时间: 2005 至 2007
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-17510093/
• 关键词: phonon; nanowire superlattice; vibrational mode; dispersion relation; phonon transmittance

We study theoretically vibrational modes in a nanowire superlattice consisting of an alternate stacking of two cylindrical layers. We focus on azimuthally symmetric torsional modes and calculate the phonon dispersion relations analytically. We also derive simple expressions for the frequency gaps generated in the nanowire superlattice. Moreover, we calculate the transmittance of phonons propagating through a nanowire superlattice with the finite number of periods. Based on our calculated results, effects of the superlattice longitudinal confinement and the radial confinement are examined.Next, we studied the phonon transmission in a double-barrier structure realized by a defect layer sandwiched between two periodic NWSLs. We focused on the torsional modes whose dispersion relations can be obtained analytically and calculated the transmittance. We can see the resonant peak in the frequency gap determined by the periodicity of the NWSL. This peak originates from the resonance with the vibrational mode localized at the defect layer. We also calculated the eigenfrequency of this localized mode. In particular, we examined how the eigenfrequency depends on the width of the defect layer. The radial confinement of the phonons generates a critical frequency, which is determined by the radius of the NWSL. When the frequency of phonons is lower than this critical frequency, the wave number defined in the defect layer becomes an imaginary number. Our results show that the localized modes can be generated only above the critical frequency.

从理论上研究了由两层柱状层交替堆积而成的纳米线超晶格中的振动模。我们以方位对称扭转模为研究对象，对声子色散关系进行了解析计算。我们还推导出了纳米线超晶格中产生的频隙的简单表达式。此外，我们还计算了有限周期数的纳米线超晶格中声子的透过率。基于我们的计算结果，考察了超晶格纵向约束和径向约束的影响。其次，我们研究了由缺陷层夹在两个周期NWSL之间实现的双势垒结构中的声子传输。重点研究了其色散关系可以解析得到的扭转模并计算了其透过率。我们可以看到由NWSL的周期性决定的频隙中的共振峰。该峰源于缺陷层振动模局域的共振。我们还计算了这种局域模的本征频率。特别是，我们研究了本征频率如何依赖于缺陷层的宽度。声子的径向限制产生一个临界频率，该频率由NWSL的半径决定。当声子频率低于此临界频率时，缺陷层中定义的波数变为虚数。我们的结果表明，只有在临界频率以上才能产生局域模。

项目成果

Acoustic phonons in nanowire superlattices: Azimuthally symmetric torsional modes

• DOI: 10.1103/physrevb.71.085303
• 发表时间: 2005-02
• 期刊: Physical Review B
• 影响因子: 3.7
• 作者: S. Mizuno

First-principles calculations of the geometry of a Zn-Sc cluster

Zn-Sc团簇几何形状的第一性原理计算

• 发表时间: 2007
• 期刊: Philosophical Magazine 87
• 作者: Tsugio Tadaki;Kouichi Kifune;Yoshiki Kubota;Hiroshi Yamaoka;Seiji Mizuno
• 通讯作者: Seiji Mizuno

Fundamentals of the phononic crystals ---Introduction to elastic waves---

声子晶体的基础知识---弹性波简介---

• 发表时间: 2008
• 作者: K. Goto;T. Shinmyozu;Seiji Mizuno;Seiji Mizuno;Seiji Mizuno;水野誠司;河野武司;Seiji Mizuno;Takeshi Kono;水野誠司;Seiji Mizuno
• 通讯作者: Seiji Mizuno

First-principles calculation of the geometry of a Zn-Sc cluster

Zn-Sc团簇几何形状的第一性原理计算

• 发表时间: 2006
• 作者: K. Goto;T. Shinmyozu;Seiji Mizuno;Seiji Mizuno
• 通讯作者: Seiji Mizuno

Localized vibrational modes generated in a superlattice with a surface and a defect layer

在具有表面和缺陷层的超晶格中产生的局域振动模式

• 发表时间: 2005
• 作者: K. Goto;T. Shinmyozu;Seiji Mizuno;Seiji Mizuno;Seiji Mizuno;水野誠司;河野武司;Seiji Mizuno;Takeshi Kono
• 通讯作者: Takeshi Kono