Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China.
Nanoscale. 2017 Dec 21;10(1):174-183. doi: 10.1039/c7nr06159e.
By constructing transport junctions using graphene-based van der Waals (vdW) heterostructures in which a zigzag-edged graphene nanoribbon (ZGNR) is sandwiched between two hexagonal boron-nitride sheets, we computationally demonstrate a new scheme for generating perfect spin-polarized quantum transport in ZGNRs by light irradiation. The mechanism lies in the lift of spin degeneracy of ZGNR induced by the stagger potential it receives from the BN sheets and the subsequent possibility of single spin excitation of electrons from the valence band to the conduction band by properly tuning the photon energy. This scheme is rather robust in that we always achieve desirable results irrespective of whether we decrease or increase the interlayer distance by applying compressive or tensile strain vertically to the sheets or shift the BN sheets in-plane relative to the graphene nanoribbons. More importantly, this scheme overcomes the long-standing difficulties in traditional ways of using solely electrical field or chemical modification for obtaining half-metallic transport in ZGNRs and thus paves a more feasible way for their application in spintronics.
通过构建基于石墨烯的范德华（vdW）异质结构的输运结，其中一个锯齿状边缘的石墨烯纳米带（ZGNR）被夹在两个六方氮化硼片之间，我们通过计算证明了一种通过光辐照在 ZGNR 中产生完美自旋极化量子输运的新方案。该机制在于 BN 片从 ZGNR 接收到的交错势引起的 ZGNR 自旋简并的消除，以及通过适当调整光子能量，电子从价带单自旋激发到导带的可能性。该方案相当稳健，因为无论我们通过垂直施加压缩或拉伸应变来减小或增大层间距离，还是相对于石墨烯纳米带在平面内移动 BN 片，我们总是能够获得理想的结果。更重要的是，该方案克服了传统方法中仅通过电场或化学修饰获得 ZGNR 中半金属输运的长期困难，从而为其在自旋电子学中的应用铺平了更为可行的道路。
