Controllable topological phase transitions

Topological insulators are a fundamentally new form of quantum matter with striking properties, such as unusual spin-polarized metallic surface states. They are potential platforms to realize a range of fundamental and practical advances, including dissipationless transport and quantum computation. Controlling the transition between conventional band insulators and topological insulators is key to realizing their potential. Moreover, it is a rare example of a phase transition not characterized by symmetry breaking, the mainstay of condensed matter physics, but rather it is rooted in the mathematical concept of topology. In this project, you will explore new ways to exploit this in condensed matter systems. You will investigate methods to drive topological phase transitions, and study the interplay of topological order with additional phases such as superconductivity or magnetism. You will use angle-resolved photoemission spectroscopy (ARPES), a powerful probe of electronic structure, to track the evolution of the bulk band structure and the emergence of helical surface states. You will make extensive use of our state-of-the-art spectroscopy lab in St Andrews, and will also perform measurements at synchrotrons in the UK, Europe and the USA.