Topological Insulators by Band-Gap Engineering

*技术摘要*本项目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子的新特性进行实验。这种支持量子化螺旋边缘模的二维量子自旋霍尔绝缘体是利用分子束外延和静电门的带隙工程创造出来的。该项目将继续探索在介观长度尺度上有趣的物理，重点是螺旋边缘模及其与超导体的界面，其中将系统地研究邻近效应和安德列夫反射。该项目将支持两名博士生的教育，在那里将接受半导体材料、纳米技术和超低温测量方面的高级培训。了解这类材料的材料科学及其拓扑性质直接关系到自旋电子学和量子信息技术。*非技术摘要*电绝缘子一般是指阻止电流流动的材料。然而，最近的研究显示了一种具有新颖性能的拓扑绝缘子。虽然电流不能通过它们，但它可以绕过它们狭窄的外缘。这种材料被称为“量子自旋霍尔拓扑绝缘体”，起着电子高速公路的作用。它是创造未来电子产品和计算机所需的积木之一。该项目将对新发现的由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相关的重要问题。这将使用最先进的纳米技术和超低温测量工具来实现。该项目将支持两名博士生在半导体材料和技术以及基础物理方面的教育。

****Technical Abstract****This project will pursue experiments on the novel properties of newly discovered topological insulators made of compound semiconductors indium arsenide and gallium antimonide. This two-dimensional quantum spin Hall insulator, which supports quantized helical edge modes, is created by band-gap engineering using molecular beam epitaxy and electrostatic gates. The project will continue to explore 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 will be systematically studied. The project will support the education of two Ph. D students, where a combination of advanced trainings in semiconductor materials, nanotechnology, and ultralow temperature measurements will be received. Understanding of materials science of this class of material and their topological properties is directly relevant to spintronics and quantum information technology. ****Non-Technical Abstract****Electrical insulators commonly refer to the 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. This project will pursue experiments on the newly discovered topological insulators made of semiconductors indium arsenide and gallium antimonide, addressing important issues relate to materials science and quantum physics. This will be accomplished using the most advanced tools of nanotechnology and ultralow temperature measurements. The project will support the education of two Ph. D students in semiconductor materials and technology, as well as fundamental physics.