Giant spin thermoelectric effects in all-carbon nanojunctions.
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.
College of Physics and Engineering, Changshu Institute of Technology and Jiangsu Laboratory of Advanced Functional materials, Changshu 215500, China. xuekh@mail.sitp.ac.cn ysliu@cslg.edu.cn.
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Yang
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Wang
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Chen
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Kuang
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Hong
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Liu
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Feng
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Wang