Plasmonics involves confining light to nanoscale structures as a collective excitation of electrons. Developing next generation devices based on plasmonics has important technological applications in communications, high-speed computing and quantum optics. Of particular interest are surface plasmon polaritons, which propagate as a surface wave and are particularly sensitive to their local environment, making them useful in sensors and communications. Typically, plasmonic meta-materials are created by etching patterns into a layer of highly conducting metal, such as gold. The periodic pattern allows critical parameters, such as the permittivity, to be manipulated and produce effects not seen in nature. Recently, a new form of surface plasmon was observed in topological insulators. These are alloys that possess topological surface states with unique properties. These Dirac plasmon modes exhibit lower losses, and coupling between spin and momentum which may have important applications in spintronics and quantum computing. These modes can be manipulated using certain surface coatings and dopants, including organic molecules.
This project will develop a new method for creating plasmonic meta-materials from topological insulators. Rather than using conventional lithography to create periodic patterns in the material, we will use a combination of organic coatings and ion doping to create regions where the topological surface state is gapped. Instead of the pattern existing as regions of vacuum and conducting surface, it exists as a contrast between regions with different topological character. As well as exploring novel plasmon physics in an exotic class of materials, this project will also develop new techniques for developing meta-materials, which will have a significant impact on the field.
The successful candidate will develop these materials using the Henry Royce Deposition System, a world leading system at the University of Leeds, and will develop the patterning methods in collaboration with the University of Manchester using the pNAME system. They will develop a range of transferable skills in lithography and materials growth, as well as an understanding of electron microscopy, electronic, optical and terahertz characterisation techniques.