Chi Feng, Fu Zhen-Guo, Liu Jia, Li Ke-Man, Wang Zhigang, Zhang Ping
School of Electronic and Information Engineering, University of Electronic Science and Technology of China, Zhongshan Institute, Shiqi District Xueyuan Road No. 1, Zhongshan, 528402, China.
Institute of Applied Physics and Computational Mathematics, No. 6 Huayuan Road, Haidian District, Beijing, 100088, China.
Nanoscale Res Lett. 2020 Apr 15;15(1):79. doi: 10.1186/s11671-020-03307-y.
We theoretically study the thermoelectric effect in a hybrid device composed by a topological semiconducting nanowire hosting Majorana bound states (MBSs) and a quantum dot (QD) connected to the left and right non-magnetic electrodes held at different temperatures. The electron-electron Coulomb interactions in the QD are taken into account by the non-equilibrium Green's function technique. We find that the sign change of the thermopower, which is useful for detecting the MBSs, will occur by changing the QD-MBS hybridization strength, the direct overlap between the MBSs at the opposite ends of the nanowire, and the system temperature. Large value of 100% spin-polarized or pure spin thermopower emerges even in the absence of Zeeman splitting in the QD or magnetic electrodes because the MBSs are coupled to electrons of only one certain spin direction in the QD due to the chiral nature of the Majorana fermions. Moreover, the magnitude of the thermopower will be obviously enhanced by the existence of MBSs.
我们从理论上研究了一种混合器件中的热电效应，该器件由承载马约拉纳束缚态（MBS）的拓扑半导体纳米线和连接到处于不同温度的左右非磁性电极的量子点（QD）组成。通过非平衡格林函数技术考虑了量子点中的电子 - 电子库仑相互作用。我们发现，通过改变量子点 - MBS 杂化强度、纳米线两端 MBS 之间的直接重叠以及系统温度，可用于检测 MBS 的热电势的符号会发生变化。即使在量子点或磁性电极中不存在塞曼分裂的情况下，也会出现高达 100% 的自旋极化或纯自旋热电势的大值，这是因为由于马约拉纳费米子的手征性质，MBS 仅与量子点中特定自旋方向的电子耦合。此外，MBS 的存在将明显增强热电势的大小。
