Geometrically induced broadening for phonon blocking at low temperatures
Geometrically induced broadening for phonon blocking at low temperatures
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DOI：
10.1103/physrevb.97.224312
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发表时间：
2018-06
影响因子：
3.7
通讯作者：
K. Hattori;Yohei Nakamura
中科院分区：
文献类型：
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作者：
K. Hattori;Yohei Nakamura
由于存在无激励间隙的鲁棒无质量模式，即使将散射机制纳入系统，声子携带的热流也倾向于在低温下存活。这成为低温下热电应用的根本障碍。在这项研究中，我们使用非平衡格林函数形式研究了在不同几何形状的导联或探针耦合的介观系统中，能量展宽对声子输运的影响。一个由谐波链组成的最小模型导出的解析理论表明，几何诱导的展宽相当大程度地抑制了低温声子输运。数值计算也证明了这种声子阻挡方案在高维实际系统中是可行的。
Because of the presence of robust massless modes with no excitation gap, 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 coupled to leads or probes in various geometries using a nonequilibrium Green's function formalism. An analytic theory derived from a minimal model consisting of a harmonic chain shows that geometrically induced broadening sizably suppresses low-temperature phonon transport. It is also demonstrated from numerical calculations that this scheme for phonon blocking is viable for realistic systems in higher dimensions.