The ability to engineer the thermal conductivity of materials allows us to control the flow of heat and derive novel functionalities such as thermal rectification, thermal switching and thermal cloaking. While this could be achieved by making use of composites and metamaterials at bulk length-scales, engineering the thermal conductivity at micro- and nano-scale dimensions is considerably more challenging. In this work, we show that the local thermal conductivity along a single Si nanowire can be tuned to a desired value (between crystalline and amorphous limits) with high spatial resolution through selective helium ion irradiation with a well-controlled dose. The underlying mechanism is understood through molecular dynamics simulations and quantitative phonon-defect scattering rate analysis, where the behaviour of thermal conductivity with dose is attributed to the accumulation and agglomeration of scattering centres at lower doses. Beyond a threshold dose, a crystalline-amorphous transition was observed.

中文翻译：

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通过选择性氦离子辐射沿着单个硅纳米线设计热导率。

设计材料导热性的能力使我们能够控制热流并获得新颖的功能，例如热精馏，热转换和热隐蔽。虽然这可以通过使用整体长度尺度上的复合材料和超材料来实现，但在微米和纳米尺度上设计热导率要困难得多。在这项工作中，我们表明可以通过选择性控制的剂量的氦离子辐照，以高空间分辨率将沿单根Si纳米线的局部热导率调节至所需值（在晶体和非晶极限之间）。通过分子动力学模拟和定量声子缺陷散射率分析可以了解其潜在机理，导热系数随剂量变化的行为归因于较低剂量下散射中心的聚集和聚集。超过阈值剂量，观察到结晶-无定形转变。