Tan Xingyi, Liu Lili, Du Gui-Fang, Fu Hua-Hua
Department of Physics, Chongqing Three Gorges University, Wanzhou, 404100, People's Republic of China.
School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China.
Phys Chem Chem Phys. 2020 Sep 8;22(34):19100-19107. doi: 10.1039/d0cp02732d.
By using nonequilibrium molecular dynamics, thermal transport through a series of parallel step-like graphene nanoribbon (GNR) junctions is investigated. The theoretical results show that the thermal current flows preferentially from wide GNRs to narrow ones, displaying a pronounced thermal rectification effect. Moreover, several step-like GNR-based devices are designed, and the thermally driven spin-dependent currents are calculated by using density functional theory combined with the nonequilibrium Green's function approach. We find that thermal spin-dependent currents with opposite flow directions are generated when a temperature gradient is applied along the GNRs, indicating the occurrence of a spin-dependent Seebeck effect (SDSE). More interestingly, a negative differential SDSE occurs in the thermal spin currents, and the odd and even law appears in the spin-dependent currents, thermopowers and thermoelectric conversion efficiencies. Our theoretical results indicate that the parallel step-like GNRs are potential candidates to design spin caloritronics devices hosting thermal rectification and multiple thermal-spin transport functionalities.
通过使用非平衡分子动力学，研究了通过一系列平行的阶梯状石墨烯纳米带（GNR）结的热输运。理论结果表明，热电流优先从宽的GNR流向窄的GNR，表现出明显的热整流效应。此外，设计了几种基于阶梯状GNR的器件，并使用密度泛函理论结合非平衡格林函数方法计算了热驱动的自旋相关电流。我们发现，当沿GNR施加温度梯度时，会产生具有相反流动方向的热自旋相关电流，这表明发生了自旋相关塞贝克效应（SDSE）。更有趣的是，热自旋电流中出现了负微分SDSE，并且在自旋相关电流、热功率和热电转换效率中出现了奇偶定律。我们的理论结果表明，平行的阶梯状GNR是设计具有热整流和多种热自旋输运功能的自旋热电子器件的潜在候选材料。
