| Project/Area Number |
17510093
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Nanomaterials/Nanobioscience
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| Research Institution | Hokkaido University |
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Principal Investigator |
MIZUNO Seiji Hokkaido University, Grad. School of Eng., Lec. (90222322)
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| Project Period (FY) |
2005 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥2,380,000 (Direct Cost: ¥2,200,000、Indirect Cost: ¥180,000)
Fiscal Year 2007: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000)
Fiscal Year 2006: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2005: ¥900,000 (Direct Cost: ¥900,000)
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| Keywords | phonon / nanowire superlattice / vibrational mode / dispersion relation / phonon transmittance |
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| Research Abstract |
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.
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