The University of Bath is inviting applications for the following PhD project supervised by Dr Marcin Mucha-Kruczynski in the Department of Physics.
Van der Waals heterostructures  are stacks of atomically thin materials (called two-dimensional atomic crystals) like graphene, hexagonal boron nitride or transition metal dichalcogenides. In contrast to conventional heterostructures, in which chemical bonding of constituent elements both modifies their properties and requires lattice matching for stability of defect-less structures, van der Waals heterostructures are glued by weak forces that do not lead to directional bonding. As a result, any two two-dimensional crystals can be placed on top of each other, allowing for unprecedented freedom in selection of components and design of new artificial materials. Moreover, two crystals can be stacked at any relative angle between their crystallographic axes and changing it can drastically modify the properties of the heterostructure, with small rotations making the difference between, for example, making the structure superconducting or not, as recently shown in the case of so called “magic-angle” twisted bilayer graphene [2,3].
From the theoretical point of view, studying the properties of stacks of misaligned atomic crystals presents some difficulties: for an arbitrary angle, the interface is incommensurate and Bloch’s theorem, the cornerstone of solid state physics, is seemingly not applicable, invalidating all standard approaches to modelling properties of crystals. Even for angles leading to commensurate ‘superstructures’, brute force computational approaches struggle because of the huge number of atoms in a unit cell so that a novel approach is necessary.
In this project, you will investigate theoretically new phenomena which emerge in van der Waals heterostructures due to the interaction between two crystals and are driven by changes in the atomistic geometry at the interface between van der Waals-coupled materials. You will develop effective models to describe electronic, optical and vibrational properties of such heterostructures at any angle and use both analytical and computational tools to search for and study situations in which many-body effects lead to novel behaviour.
The project will be realised within the group led by Dr Marcin Mucha-Kruczynski and might involve collaboration with other theoretical or experimental groups in the UK or abroad. For more detailed information on the research and the group, please visit http://people.bath.ac.uk/mlmk20/
Applicants should hold, or expect to receive, a First Class or good Upper Second Class Honours degree (or the equivalent) in Physics. A master’s level qualification would also be advantageous - Theoretical Physics preferred or Theoretical/Quantum Chemistry (or other closely related field). A keen interest in theoretical condensed matter physics and a strong work ethic are essential. Also required is basic programming experience (knowledge of Matlab/Mathematica will be beneficial but is not necessary).
Enquiries and applications:
Informal enquiries are welcomed and should be directed to Dr Marcin Mucha-Kruczynski, [email protected]
Formal applications should be made via the University of Bath’s online application form for a PhD in Physics: https://samis.bath.ac.uk/urd/sits.urd/run/siw_ipp_lgn.login?process=siw_ipp_app&code1=RDUPH-FP01&code2=0014
More information about applying for a PhD at Bath may be found here: http://www.bath.ac.uk/guides/how-to-apply-for-doctoral-study/
Anticipated start date: 28 September 2020.
Research Council funding is available for an excellent UK or EU student who has been ordinarily resident in the UK since September 2017. For more information on eligibility: View Website.
Funding will cover UK/EU tuition fees, maintenance at the UKRI doctoral stipend rate (£15,009 per annum tax-free in 2019/20, increasing annually in line with the GDP inflator) and a training support grant (£1,000 per annum) for a period of up to 3.5 years.
We also welcome all-year-round applications from self-funded candidates and candidates who can source their own funding.
1] Geim and Grigorieva, Van der Waals heterostructures, Nature 499, 419 (2013).
 Cao et al., Unconventional superconductivity in magic-angle graphene superlattices, Nature 556, 43 (2018).
 Cao et al., Correlated insulator behaviour at half-filling in magic-angle graphene superlattices, Nature 556, 80 (2018).