石墨烯线缺陷局域形变对谷输运性质的影响  

Influence of local deformation on valley transport properties in the line defect of graphene

作　　者：崔磊[1] 刘洪梅 任重丹 杨柳 田宏玉 汪萨克 Cui Lei;Liu Hong-Mei;Ren Chong-Dan;Yang Liu;Tian Hong-Yu;Wang Sa-Ke(College of Information Engineering,Suqian University,Suqian 223800,China;School of Physics and Electronic Engineering,Linyi University,Linyi 276005,China;Department of Physics,Zunyi Normal College,Zunyi 563006,China;College of Science,Jinling Institute of Technology,Nanjing 211169,China)

机构地区：[1]宿迁学院信息工程学院,宿迁223800 [2]临沂大学物理与电子工程学院,临沂276005 [3]遵义师范学院物理与电子科学学院,遵义563006 [4]金陵科技学院理学院,南京211169

出　　处：《物理学报》2023年第16期190-197,共8页Acta Physica Sinica

基　　金：宿迁市重点实验室项目(批准号:M202109);宿迁学院科研平台(批准号:2021pt04);国家自然科学基金(批准号:12264059,12004149);山东省自然科学基金(批准号:ZR2022MA026,ZR2020QA062,ZR2023MA027);江苏省自然科学基金(批准号:BK20211002);江苏省“青蓝工程”资助的课题.

摘　　要：石墨烯线缺陷在谷电子学中有非常重要的应用.实验发现,线缺陷附近存在局域形变.当前研究普遍认为,由于形变较小,对近邻跳跃能的影响小于5%,局域形变对谷输运性质的影响可以忽略不计.基于第一性原理计算和非平衡格林函数方法,本文研究了局域形变对两种不同构型线缺陷谷输运性质的影响.结果发现,对于58环线缺陷,在较低能量下,局域形变对谷隧穿系数的影响并不明显,然而,在较高能量下局域形变的影响非常明显,谷隧穿系数最大值并没有随着能量升高而减小,而是在很大能量范围内都保持不变.进一步研究表明,该效应是由与线缺陷相连的C-C键长发生改变造成的.通过构建两个平行线缺陷,可以在很大的角度范围内都实现100%谷过滤效果.相比之下,局域形变对57环线缺陷谷隧穿系数的影响非常小.The line defect of graphene has significant applications in valleytronics,which has received extensive attention in recent years.It is found experimentally that there exists local deformation around the line defect.Current studies generally believe that the influence of local deformation on the valley transport properties can be negligible,because the modifications to the nearest neighbour hopping energy is less than 5%under the small deformation.Based on the first-principles calculations and the non-equilibrium Green’s function method,we investigated the effect of local deformation on the valley transport properties of two different kinds of line defects,the 58 ring line defect and the 57 ring line defect.It is found that for the 58 ring line defect,the effect of local deformation on the valley transmission coefficient is not evident at lower energies.However,at higher energies,the impact of local deformation is obvious,and the maximum valley transmission coefficient does not decrease with increasing energy,but can be maintained 1 within a large energy range.In contrast,the influence of local deformation on the valley transmission coefficient of the 57 ring line defect indeed can be negligible,regardless of the level of energy.Further investigation indicates that the change of the C-C bond length connected to the two defect atoms in the 58 ring plays a key role in the transmission of the valley states across the line defect.If this part of the influence is not taken into account,the valley transmission coefficient is nearly unaffected by the local deformation.The valley state enters the right side of the line defect directly through the bond connected to the line defect,so the change in bond length connected to the line defect has a significant impact on the valley transmission.This special structure does not exist in the 57 ring,where the valley states will have to pass through a narrow region containing 57 ring to enter the right side of the line defect,resulting in different valley scattering phenomena.By c

关 键 词：石墨烯 线缺陷 第一性原理计算 局域形变 谷过滤 

分 类 号：O469[理学—凝聚态物理]