###Search for new topological states in implanted acceptor structures
Project ID: 2228bd1058 (You will need this ID for your application)
Research Theme: Physical Sciences
UCL Lead department: London Centre for Nanotechnology (LCN)
Lead Supervisor: Andrew Fisher
Project Summary:
Why this research is important. One of the most exciting discoveries in condensed matter physics in the last ten years is that phases of matter are characterised by their topology, as well as their symmetry. Initially a theorists’playground, this area is increasingly making contact with experiments to demonstrate topological phenomena in real systems. This project would build on a new connection with one of the most precise material fabrication technologies known: atomistically precise placement of dopants in semiconductors by scanning tunnelling microscope (STM) lithography. Who we will be working with. This is a theoretical project to be performed in close collaboration with the LCN’s STM lithography group (Curson, Schofield – EEE/P&A joint appointments – and Stock – EEE) who are world leaders in the area, having co-developed the initial process of P implantation and most recently demonstrated improved resolution and success rates using As implantation. They are aiming to develop their techniques to work with acceptors, as well as donors, motivating the present project. What we will be doing. Our group recently demonstrated that a two-dimensional honeycomb array of acceptor impurities in a semiconductor forms a topological insulator, using the spin-orbit coupling in the host material’s valence band to create designer topological materials with non-trivial spin textures for the first time. Building on this discovery, we would • Study how to control the topological properties using electric fields from nearby gate electrodes; • Search for new experimental signatures of the topological state; • Seek realisations of other topological states, for example: higher-order topological insulators, Weyl metals, and ultimately lattices hosting topologically protected quantum bits (qubits). Who we are looking for. A student with a strong background in theoretical physics or chemistry, motivated to work on fundamental problems in topological systems but also to work with experimentalists to find physical realisations.