Giant spin thermoelectric effects in all-carbon nanojunctions.
Giant spin thermoelectric effects in all-carbon nanojunctions.
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DOI：
10.1039/c5cp02779a
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发表时间：
2015-08
期刊：
影响因子：
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通讯作者：
Xifeng Yang;H. L. Wang;Y. S. Chen;Y. Kuang;X. Hong;Y. S. Liu;Jinfu Feng;Xinxin Wang
中科院分区：
文献类型：
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作者：
Xifeng Yang;H. L. Wang;Y. S. Chen;Y. Kuang;X. Hong;Y. S. Liu;Jinfu Feng;Xinxin Wang
我们研究了由碳原子链连接的石墨烯纳米片(GNF)和锯齿形边缘石墨烯纳米带(ZGNR)构建的全碳纳米结的热旋性质。第一性原理计算表明，在费米能级上，声子热导远弱于电子热导，甚至在低温区声子热导也只有电子热导的几个百分点。同时，由于半金属性质的出现，碳基器件在费米水平上具有良好的自旋输运特性。此外，单自旋Seebeck系数在费米能级有较大的值。这些事实最终导致了自旋热电优值系数(FOM)ZST的显著提高。通过控制碳链长度和温度，ZST的最大值可以达到30。此外，我们还发现，室温ZST随碳链长度的变化呈现奇偶效应，且始终大于电荷热电FOM Zct。
We examine the thermospin properties of an all-carbon nanojunction constructed by a graphene nanoflake (GNF) and zigzag-edged graphene nanoribbons (ZGNRs), bridged by the carbon atomic chains. The first-principles calculations show that the phonon thermal conductance is much weaker than the electron thermal conductance at the Fermi level, and even the former is a few percent of the latter in the low-temperature regime. In the meantime, the carbon-based device possesses an excellent spin transport property at the Fermi level due to the appearance of half-metallic property. Furthermore, the single-spin Seebeck coefficient has a larger value at the Fermi level. These facts ultimately result in a significant enhancement of spin thermoelectric figure of merit (FOM) ZST. By controlling the carbon-chain lengths and the temperature, the maximal value of ZST can reach 30. Moreover, we also find that the room temperature ZST displays an odd-even effect with the carbon-chain lengths, and it is always larger than the charge thermoelectric FOM ZCT.