拓扑绝缘体表面电子-声子相互作用机理的实验研究

项目名称： 拓扑绝缘体表面电子-声子相互作用机理的实验研究

项目编号： No.11304367

项目类型： 青年科学基金项目

立项/批准年度： 2014

项目学科： 数理科学和化学

项目作者： 朱学涛

作者单位： 中国科学院物理研究所

项目金额： 30万元

中文摘要： 拓扑绝缘体是一种新的量子物质态，其体内的能带结构类似于普通绝缘体一样具有能隙而其表面则具有导电的金属态。拓扑绝缘体最令人关注的一种性质是其表面电子态很难被非磁性的杂质所破坏，从而使这种表面电子态非常稳定。这就使电子-声子的相互作用成为了拓扑绝缘体表面电子态最重要的散射机制。因此，对拓扑绝缘体表面电声耦合的研究对其任何潜在的应用都是非常重要的。然而，当前的研究对拓扑绝缘体表面电声耦合的强度存在很大的分歧，特别是对其散射机制，还没有明确的结论。本项目将结合角分辨光电子能谱仪和新型高分辨低能电子能量损失谱仪，对拓扑绝缘体表面的电声耦合的机理进行系统全面的研究，研究体系包括典型的三维拓扑绝缘体材料Bi2Se3和Bi2Te3等。我们还将发展相关的方法来解析出拓扑绝缘体表面电声耦合详细的物理图像，包括电子的跃迁路径以及参与相互作用的具体声子模式。

中文关键词： 拓扑绝缘体；集体元激发；电子-声子耦合；电子能量损失谱；角分辨光电子能谱

英文摘要： Topological insulators (TIs) are electronic materials that have a bulk band gap like an ordinary insulator but have protected conducting states on their surface. One of the most interesting properties of TIs is their spin helicity, whereby the spin is locked normal to the wave vector of the surface electronic state. The topological surface states should be very stable in TIs, since these spin-textured surface states are robust against spin-independent backscattering. Consequently, electron-phonon coupling (EPC) should be the dominant scattering mechanism for surface electronic states at finite temperatures. Hence, the study of EPC in TIs is of exceptional importance in assessing any potential applications. However, a consensus about the EPC strength on the surface of TIs has not been achieved by current studies, since conflicting values have been reported. And the EPC mechanism is still not clear. In this proposal we will employ Angle Resolved Photoemission Spectroscopy and state-of-the-art High Resolution Electron Energy Loss Spectroscopy to study EPC mechanism on the surface of typical three dimensional TIs, such as the systems of Bi2Se3 and Bi2Te3. We will also develop the related theory to figure out the details of the EPC physical picture such as the transition path of the electrons and the evolved specific

英文关键词： Topological Insulator；Collective Excitation；Electron-phonon Coupling；HREELS；ARPES