Topological Insulators by Band-Gap Engineering

非技术描述：电绝缘体通常被认为是防止电流流动的材料。然而，最近的研究表明，一类拓扑绝缘体具有新颖的性质。虽然电流不能通过它们，但它可以绕着它们狭窄的外缘流动。这种材料被称为“量子自旋霍尔拓扑绝缘体”，充当电子高速公路。 它是创造未来电子产品和计算机所需的基石之一。在这个项目中，主要研究人员将对新发现的由化合物半导体砷化铟和锑化镓制成的拓扑绝缘体进行实验，解决与材料科学和量子物理有关的重要问题。对这类材料及其拓扑性质的理解直接关系到自旋电子学和量子信息技术。技术要点：二维拓扑绝缘体，支持量子化螺旋边缘模式，是通过使用分子束外延和静电门的带隙工程创建的。该项目在介观长度尺度上探索有趣的物理学，重点是螺旋边缘模式及其与超导体的界面，系统地研究邻近效应和Andreev反射。研究的重点是寻找混合拓扑绝缘体-超导体约瑟夫森结中的Majorana束缚态。实验研究工作在一个非常干净的模型系统中解决了基本现象及其物理学问题。该项目支持两名博士的教育。学生，在那里他们接受半导体材料，纳米技术和超低温测量的高级培训的组合。

Nontechnical description:Electrical insulators are commonly recognized as materials that prevent the flow of electricity. However, recent research demonstrates a type of topological insulators which has novel properties. Although electricity cannot flow through them, it can flow around their narrow outer edges. The material, called a "quantum spin Hall topological insulator", acts as an electron superhighway. It is one of the building blocks needed to create future electronics and computers. In this project the principle investigator will perform experiments on the newly discovered topological insulators made of compound semiconductors indium arsenide and gallium antimonide, addressing important issues relate to materials science and quantum physics. Understanding of materials science of this class of material and their topological properties is directly relevant to spintronics and quantum information technology.Technical descripton:The two-dimensional topological insulator, which supports quantized helical edge modes, is created by band-gap engineering using molecular beam epitaxy and electrostatic gates. The project is exploring interesting physics at the messoscopic length scale, with the focus on the helical edge modes and their interface with superconductors, where proximity effect and Andreev reflection are being systematically studied. Major focus of the study is searching for Majorana bound states in hybrid topological insulator-superconductor Josephson junctions. The experimental research work addresses fundamental phenomenon and its physics in a very clean model system. The project supports the education of two Ph.D. students, where they receive a combination of advanced training in semiconductor materials, nanotechnology, and ultra-low temperature measurements.