High temperature superconductivity has the potential to transform use of electrical power, enabling low carbon technologies such as fusion reactors and electric airplanes. Exploitation of superconductivity is aided by a greater understanding of the fundamental physics of these materials, enabling the search for new, better materials. There are many theories for the fundamental reason why some materials superconduct particularly at high temperature and working out which one of these is correct is a strong focus of research world-wide. One prominent theory is that superconductivity is strongly enhanced by the presence of quantum-critical fluctuations from a competing order such as antiferromagnetism. Here we will investigate such potential quantum critical points in superconducting materials.
Superconducting materials are often made superconducting by tuning their chemistry (for example, by changing the oxygen content (x) in the cuprate superconductor YBa2Cu3O6+x) however, superconductivity can also be tuned by applying high pressure. The latter route is much cleaner and controllable because a single sample can be used without adding impurity atoms. In this project, we will use a high pressure cell to tune superconductivity in materials such as the iron-based, cuprate and heavy-fermion systems; varying the superconducting transition temperature and at the same time measuring the superconducting magnetic penetration depth which is proportional to the effective mass of the superconducting electrons. A key signature of a quantum critical point is the divergence of the effective mass, and so this will provide key evidence for this in the systems we will study.
During this PhD you will learn about superconductivity, experimental techniques for low temperature physics including high pressure techniques, and calculations necessary to understand the data (such as modelling reconstructions and distortions of the Fermi surface). Bristol has extensive high performance computing facilities available for this numerical modelling.
Visit http://www.bristol.ac.uk/physics/research/qsm/postgrad/ for more details.
Candidates should have completed an undergraduate degree (minimum 2(i) honours or equivalent) in Physics, and have a strong interest in experimental physics. Specific knowledge about superconductivity is not required.
How to apply:
Please make an online application for this project at http://www.bris.ac.uk/pg-howtoapply. Please select Physics PhD on the Programme Choice page. You will be prompted to enter details of the studentship in the Funding and Research Details sections of the form. Please make sure you include the title of studentship and the contact supervisor in your Personal Statement.
Professor Antony Carrington ([Email Address Removed])
Assoc. Prof. Sven Friedemann ([Email Address Removed])