A PhD project offered by Dr Gunnar Möller
(see longer description) (PDF of project) (about the supervisor)
(to application instructions) (to departmental advertisement)
Short project description:
Twisted graphene multilayers have been heralded for the discovery of new types of correlated insulators [1] and superconducting phases [2], triggering a wave of excitement about these spectacular new regimes of strong correlation physics. A small twist between two stacked graphene layers leads to huge ‘moiré’ unit cells with 1000s of atoms, but only few degrees of freedom are relevant at low energies and reduce to a low-energy manifold of eight flat bands near the magic twist angle. There has been much work on this system, but a definite quantitative understanding of these interacting regimes in multiband materials remains lacking.
To unravel strong correlation physics in multiband models such as these, the idea for this project is to generalise the connected determinantal Monte-Carlo (cDet) approach [3]. The cDet algorithm has already yielded definite answers in many difficult to understand regimes for the cae of the single band Hubbard model [4].
During this project, we will first benchmark the approach on simple limiting cases, and will then proceed to more realistic two-band models. Ultimately, we will study advanced applications to multi-band models of twisted graphene multilayers. The work will extend an established code-base for diagrammatic Monte-Carlo algorithms developed in Dr Möller’s group, and will benefit from established national and international collaborations.
Project supervisor: see directory for Dr Gunnar Möller and a longer intro.
More information:
You can find more background here: long project description.
To apply, please use the University of Kent postgraduate application for a PhD degree in Physics, and mention the project title and name of the supervisor who you would like to work with. Use the application form to motivate your interest in the project, and how you are qualified. See the group advert for more instructions.
Bibliography:
[1] Cao, Y. et al. Correlated insulator behaviour at half-filling in magic-angle graphene superlattices. Nature 556, 80–84 (2018).
[2] Cao, Y. et al. Unconventional superconductivity in magic-angle graphene superlattices. Nature 556, 43–50 (2018).
[3] Rossi, R. Determinant diagrammatic Monte-Carlo algorithm in the thermodynamic limit. Physical Review Letters 119, 045701 (2017).
[4] Fedor Šimkovic, I. V. et al. Extended crossover from a Fermi liquid to a quasi-antiferro-magnet in the half-filled 2D Hubbard model. Physical Review Letters 124, 017003 (2020).
(see longer description) (about the supervisor) (to application instructions) (to departmental advertisement)