Song Lingling, Yang Zhihong, Liu Lu, Yuan Liwei, Zhao Han, Chen Xing, Zhang Yan, Zheng Xiaohong
School of Electronic Science and Applied Physics, Hefei University of Technology, Hefei 230601, People's Republic of China.
Key Laboratory of Materials Physics, Institute of Solid State Physics, HFIPS, Chinese Academy of Sciences, Hefei 230031, People's Republic of China.
J Phys Condens Matter. 2021 Apr 26;33(19). doi: 10.1088/1361-648X/abed65.
Although many schemes have been proposed to obtain full half-metallicity in zigzag silicene nanoribbons with edge monohydrogenation (H-H ZSiNRs) by chemical modification, the resulted negligible energy difference between the antiferromagnetic (AFM) and ferromagnetic (FM) configurations makes the half-metallicity hardly observable practically. In this work, based on density functional calculations, we find that the ZSiNRs with edge dihydrogenation (H2-H2 ZSiNRs) can be tuned to be half-metallic by replacing the central two zigzag Si chains with two zigzag Al-P chains, and more importantly, the FM-AFM energy difference is significantly increased compared with the H-H cases. The obtained half-metallicity originates from the different potential between two edges of the ribbon after doping, which results in the edge states of two spin channels shifting oppositely in energy. This mechanism is so robust that the half-metallicity can always be achieved, irrespective of the ribbon width. Our finding provides a fantastic way for achieving stable half-metallicity in ZSiNRs.
尽管已经提出了许多方案，试图通过化学修饰在具有边缘单氢化的锯齿形硅烯纳米带（H-H ZSiNRs）中实现完全半金属性，但反铁磁（AFM）和铁磁（FM）构型之间产生的可忽略不计的能量差使得半金属性在实际中几乎难以观察到。在这项工作中，基于密度泛函计算，我们发现通过用两条锯齿形Al-P链取代中心的两条锯齿形Si链，具有边缘双氢化的ZSiNRs（H2-H2 ZSiNRs）可以被调谐为半金属性，更重要的是，与H-H情况相比，FM-AFM能量差显著增加。所获得的半金属性源于掺杂后纳米带两条边缘之间不同的势，这导致两个自旋通道的边缘态在能量上反向移动。这种机制非常稳健，无论纳米带宽度如何，总能实现半金属性。我们的发现为在ZSiNRs中实现稳定的半金属性提供了一种绝佳的方法。
