Topological effects in high magnetic fields

This proposal aims to explore the fundamental properties of new candidate systems of topological insulators in highly crystalline materials by using high magnetic fields, applied strain and low temperatures where quantum effects can be tested. Topological insulators are a new phase of matter. Due to the strong spin-orbit interaction, these electronic systems have insulating bulk properties while maintain topologically protected metallic surfaces on their surfaces or edges. In ordinary materials, backscattering, in which electrons take a turn back owing to collisions with crystal defects, thus reducing the current flow and increasing its resistance. On the surface of topological insulators, backscattering processes are completely suppressed, so charge transport is in a low-dissipation state with exceptional transport mobility and reduced energy consumption, which is extremely attractive for semiconductor devices. As a result of unintended doping from crystal imperfections, however, residual bulk carriers are always present in the actual samples and often dominate the total conductivity. Low-dimensional nanostructures, with a large surface-to-volume ratio, provide attractive systems for transport studies, because the contribution from surface carriers is much greater than that from bulk crystals, and are therefore most relevant to electronic device applications. This research will explore the fundamental characteristics of the electronic and magnetic properties both in bulk and thin film form using nanoscale tools. This funding will develop additional expertise in designing nanoscale devices to enrich the current work in quantum materials and make significant steps towards material design and control.

The proposed research is in the emerging area of topological insulators that are potential candidates for future electronic devices due to their low dissipative charge transport and full spin polarisation that are likely to be realized at room temperature. These new materials, like graphene, are likely to revolutionize the miniaturization of conventional electronics and furthermore pave the way towards significant applications in spintronics and quantum computation. The findings of our research will have significant impact, in particular the academic community who actively try to understand the behaviour of topological insulators, and electronics industry that is in search of a replacement for the conventional CMOS approach. Not only would topological insulators solve the heat dissipation problem that will become critical following further the predicted device scaling, radically new device concepts might also be feasible that involve spin-polarized currents and even quantum computation.

Training highly qualified personnel for academia and industry is a direct impact of our research. Students and PDRAs learn to use all our existing experimental techniques in magnetic fields, to develop new experiments and software, become proficient in first principle calculations and structural analysis, device nanofabrication as well as learn to become good science communicator and participate in outreach events in the department and local schools. Outreach activities will be promoted via the website though videos and developing new hands-on experiments to be used in local schools.

While there has been significant research effort, in particular abroad, new materials with even better properties have been proposed in order to reduce the impurity levels and to control the surface states. The aim of this proposal is therefore to make step-changing improvements in the fundamental understanding of the topological insulator by using available low temperature and high magnetic field techniques and combining this with material synthesis controlled at atomic scale.

Direct contact with industry will be promoted via the Impact Advisory group of Quantum Materials that has representative from Oxford Instruments, Cryogenics, Samsung though a series of poster presentations, talks, visits to their facilities. INSPIRE platform will provide also mentoring and promote links with relevant industry to the project.