| Project/Area Number |
18K03977
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Multi-year Fund |
|---|
| Section | 一般 |
|---|
| Review Section |
Basic Section 19020:Thermal engineering-related
|
|---|
| Research Institution | Osaka University |
|---|
Principal Investigator |
|
|---|
| Project Period (FY) |
2018-04-01 – 2021-03-31
|
| Project Status |
Completed (Fiscal Year 2020)
|
| Budget Amount *help |
¥3,510,000 (Direct Cost: ¥2,700,000、Indirect Cost: ¥810,000)
Fiscal Year 2020: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000)
Fiscal Year 2019: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000)
Fiscal Year 2018: ¥2,210,000 (Direct Cost: ¥1,700,000、Indirect Cost: ¥510,000)
|
|---|
| Keywords | フォノン / 熱輸送 / 熱コンダクタンス / 熱伝導度 / 自己エネルギー |
|---|
| Outline of Final Research Achievements |
Because of the presence of massless modes, the heat current carried by phonons tends to survive at low temperatures even when scattering mechanisms are incorporated into the system. This becomes a fundamental obstacle to thermoelectric applications at low temperatures. In this study, we investigate the effect of energy broadening on phonon transport in mesoscopic systems coupling to external reservoirs such as leads and probes in various geometries using a nonequilibrium Green’s function formalism. An analytic theory shows that geometrically induced broadening sizably suppresses low-temperature phonon transport in a harmonic chain. Numerical calculations demonstrate that this scheme for phonon blocking is viable for realistic systems in higher dimensions. It is also shown that in the presence of self-consistent reservoirs, normal transport emerges for a linear self-energy in arbitrary dimensions, while nonlinear higher-order ones lead to anomalous transport in low dimensions.
|
| Academic Significance and Societal Importance of the Research Achievements |
熱電効果の新しいプラットフォームとして、ナノワイヤなどのナノ構造が注目されている。ナノ構造では、電子系の低次元化や熱伝導の抑制による効率向上が期待される。本研究では、従来にない新たな方法論として、自己エネルギーの幾何学的制御によるフォノン・ブロッキングを提案し、その有効性を理論的に実証した。本研究からは、熱電発電・冷却の飛躍的効率化に向けたブレークスルーが期待される。また、本研究の成果をまとめた論文は世界的に権威のある学術誌Physical Reviewに掲載されており、数世紀以上の長きにわたり未解明な問題であるFourierの法則に対しても重要な示唆を与えている。
|
