【作者】 王惠；

【导师】 安兴涛；

【作者基本信息】 河北科技大学 ， 凝聚态物理， 2013， 硕士

【摘要】 在当前的凝聚态物理领域中，拓扑绝缘体的研究己经成为一个热点。它是一种新物态，既与普通绝缘体一样具有能隙，又在边界处具有边缘金属态，而这种无能隙的金属态决定于体电子态的拓扑结构，而且其色散关系是线性的。因为这种独特的能带结构以及无质量狄拉克费米子所具有的特殊性质，引起了人们对拓扑绝缘体的广泛关注。人们期望能够通过研究拓扑绝缘体的输运性质，在实验中观测到其表面或边界处的金属态，并探索它实际的应用前景，而且这些新材料特殊的物理性质将对量子计算和自旋电子学等领域的发展具有巨大的推动作用。本文对拓扑绝缘体表面上台阶势鱼的电子输运性质进行了研究，我们从狄拉克方程出发，对拓扑绝缘体表面上台阶势鱼的波函数进行了分析，并且利用传递矩阵理论对台阶势鱼中电子的透射概率和电导进行了计算。我们发现拓扑绝缘体表面中透射概率随电子入射角变化的曲线中共振峰个数的多少与其鱼宽有关，鱼宽越大，共振峰的个数越多，而且拓扑绝缘体表面中的透射概率由势鱼的高度决定，并存在克莱因隨穿。我们利用传递矩阵理论和Landaiier-Biittiker公式计算台阶势鱼中的电导，出现了共振隨穿现象，我们还发现电导随台阶势鱼高度差的变化出现了开关效应，因此我们就可以通过调节费米能级以及台阶势鱼高度差来控制电导。更多还原

【Abstract】 Recently, the research of topological insulators has become focus in the field of condensedmatter physics. It is a kind of new material that has a energy gap in the bulk such as that inordinary insulators and gapless helical edge or metallic surface states on the boundary,which depends on the topology of the electronic state. Moreover, the electron in thesurface possess linear dispersion relation. Topological insulators have attracted increasingattentions due to its unique band structure and the special properties of massless Dimefermion. It is expected that the metallic state of the surface or boundary is observed and itspractical application is explored. The special physical properties of these new materialshave a significant impact for the quantum computing and the spintronics, etc.In this paper, we study the properties of the electronic transport through the stepbarrier on the surface of topological insulator. We starting from the Dirac equationanalyzed the wave function of the step barrier on the surface of topological insulator, andcalculated the the probabilities of the transmission and conductance of the step barrier. Wefound that the number of resonance peaks in the transmission about the surface oftopological insulator related to the barrier width, the wider the barrier, the more thenumber of peaks. We also found that the transmission probability of the surface oftopological insulator determined by the height of the barrier and there exist Kleintunneling. We calculated the conductance in the step barrier using the transfer matrixtheory and the formula of Landauer-Buttiker. We found that there exist the resonanttunneling phenomena. As the difference between the high and low potentials of the stepbarrier changes, the conductance exists the switch effect. Therefore we can control theconductance by adjusting the Fermi level and the difference between the high and lowpotential of the step barrier.更多还原