- 无标题文档
查看论文信息

中文题名:

 层间耦合对双层graphene能带结构的影响    

姓名:

 储昭栋    

保密级别:

 公开    

学科代码:

 070201    

学科专业:

 物理学    

学生类型:

 学士    

学位:

 理学学士    

学位年度:

 2012    

学校:

 北京师范大学    

校区:

 北京校区培养    

学院:

 物理学系    

第一导师姓名:

 何林    

第一导师单位:

 北京师范大学物理学系    

提交日期:

 2012-05-17    

答辩日期:

 2012-05-24    

外文题名:

 Effect of Interlayer Coupling on the Band Structure of Twisted Bilayer Graphene    

中文关键词:

 TBG ; 紧束缚近似 ; 能量结构 ; 层间耦合作用    

中文摘要:
本文中,主要讲述通过紧束缚近似及其二次量子化,建立数学模型,来求解单层石墨烯(SLG)、双层石墨烯(BLG)、双层有夹角的石墨烯(TBG)的能带结构。在对SLG的模型构建中,我们考虑到了次近邻间的耦合强度,得出其能量色散关系解析式,其结果与已有的科研文献结果相符的很好。对于BLG,其能量色散关系为二次型,层间加置偏压后,其能带将会打开一个可调控的能隙。我们在计算TBG的模型后,得出其结果与AB堆垛方式的BLG不一样,倒和SLG有相同之处。我们得到:(a)费米面附近的能量呈线性色散关系;(b)层间外加偏压后,不会打开能隙;(c)层间耦合作用越强,低能区的两个范霍夫奇异点的距离越近;(d)小角度时,TBG的费米速度随层间夹角变大而变大,逐渐趋近SLG的费米速度。然而TBG的理论结果(d)与最新的实验结果不符合,因此我们对模型做出了相关修正。
外文摘要:
In this thesis, we studied the dispersion of the electronic bands in the single-layer graphene (SLG), bilayer graphene (BLG) and the twisted bilayer graphene (TBG) by the tight-binding approximation. For the calculation of SLG, we derive an analytic expression for the tight-binding dispersion including up to the second-nearest neighbors, and the results are consistent with what have been published in literature. For BLG, we find its dispersion of the electronic bands is quadratic. When applying a gate bias, we demonstrate that the electronic gap of BLG can be controlled externally. We consider a graphene bilayer with a relative small angle rotation between the layers. Contrary to what happens in an AA stacked bilayer and in accord with observations in monolayer graphene, we find: (a) the low energy dispersion is linear, as in a single layer; (b) an external electric field, perpendicular to the layers, does not open an electronic gap; (c) the more powerful the interlayer coupling is, the closer the distance is between two VHS; (d) the Fermi velocity of it can be significantly smaller than the single-layer value. However, based on the discrepancy between the model predictions in (d) and recent experiment results, thus the model is further revised in the article.
参考文献总数:

 24    

插图总数:

 29    

插表总数:

 4    

馆藏号:

 本070201/1208    

开放日期:

 2012-05-31    

无标题文档

   建议浏览器: 谷歌 360请用极速模式,双核浏览器请用极速模式