Postgraduate Opportunities

Supervisor: Professor Jennifer McManus

Applications are invited for a PhD studentship, co-funded by a biotech company and EPSRC and based in the Soft Matter and Biophysics group in the School of Physics at the University of Bristol. This is an experimental biological physics project, employing a fundamental understanding of biomolecule interactions to generate new strategies for formulation of next generation biotherapeutics.

More information about the research group and a list of publications can be found here: https://www.bristol.ac.uk/people/person/Jennifer-McManus-4837d47c-f6a4-4f9c-b3be-e498cec71b74/

Supervisor: Professor Nigel Hussey

Supervisor: Professor Stephen Hayden

Supervisor: Professor Nigel Hussey

Supervisor: Dr. Sven Friedemann

Supervisor: Dr. Sven Friedemann

Superconductivity is not restricted to low temperatures as has been demonstrated by the discovery of transition temperatures up to 260 K in LaH10 [1,2]. This raises the prospect of superconductivity at even higher transition temperatures. However, pressures of more than 150 GPa are currently required to stabilise hydride high-temperature superconductors. The focus is now on superconductivity at lower pressures – ideally ambient conditions. Recently, the group of Sven Friedemann has discovered superconductivity in La4H23 at a pressure below 100 GPa (see figure) [3].

Novel ternary hydrides are predicted to be high-temperature superconductors at low and ambient pressure. For instance, high-temperature superconductivity with Tc between 65 and 160 K at ambient pressure is expected in in Mg2IrH6 [4,5]. Indeed, theory and computational work are a main driver for progress.

In this project, you will focus on synthesis and experimental characterisation of novel lanthanum and ternary hydride compounds. The work will be in close collaboration with the group of Chris Pickard at the University of Cambridge who is world-leading in computational studies of hydride superconductors.

You will employ thin-film methods to prepare samples and to fabricate electrodes for resistance measurements [3,6,7]. In addition to the thin-film methods, you will gain experience on transport and magnetic measurements, crystallography with X-ray scattering, and high-pressure methods. You will work at the University of Bristol, use international facilities like the European Synchrotron (ESRF) and enjoy regular exchange with the group of Prof. Pickard.

[1] Drozdov, A. P. et al. Nature 569, 528–531 (2019).

[2] Somayazulu, M. et al. Phys. Rev. Lett. 122, 027001 (2019).

[3] Cross, S. et al. Phys. Rev. B 109, L020503 (2024).

[4] Dolui, K. et al. Phys. Rev. Lett. 132, 166001 (2024).

[5] Sanna, A. et al. npj Computational Materials 10, 44 (2024).

[6] Osmond, I. et al. Phys. Rev. B 105, L220502 (2022).

[7] Buhot, J. et al. Phys. Rev. B 102, 104508 (2020).

Supervisor: Dr. Sven Friedemann

Unconventional superconductors may enable superconductivity at ambient conditions. With the discovery of La3Ni2O7 in 2023, a third class of unconventional high-T_c materials is now established alongside cuprates and iron-pnictides[1,2]. Experiments and theory suggest that superconductivity is mediated by electronic interactions like spin and nematic fluctuations in the latter two classes whilst conclusive experiments on La3Ni2O7 are still lacking. These fluctuation support energy scales equivalent to temperatures above ambient and hence can lead to stronger electron pairing and higher T_c. Generally, better understanding is required of how strong coupling arises and how competing instabilities are avoided.

In this project, you will work on transport, magnetic, and crystallographic studies of La3Ni2O7 and related nickelates. These studies will extract parameters like the coherence length ξ, the London penetration depth λ_L, the critical current density j_c, characteristics of the gap Δ, and determine whether multiple gaps are present in the superconducting state. This insight will help to identify of the pairing channel and hence for the mechanism of superconductivity.

The project will benefit from close collaboration with Dr Dharmalingam and Prof. Boothroyd both at the University of Oxford. Dr Dharmalingam has already grown single crystals of La3Ni2O7 that that you will study in this project. You will work with Dr Dharmalingam to characterise and select samples for high-pressure studies.

Supervisor: Dr. Chris Bell

Supervisor: Dr. Shuqiu Wang

The search for emergent novel states in quantum materials with a kagome lattice is a wide-open frontier in condensed matter physics. The interplay of frustrated geometry, electron correlations, and non-trivial topology paves the way for discovering new phases of quantum matter, such as topological magnets and topological semimetals. Further advances in the research on KAMs hinge on three key challenges:

• Precisely detecting electronic structures imposed by electron interactions.
• Identifying the fundamental origin of emergent quantum phases, such as charge-order and topological phases.
• Discovering new states and phases via new materials.

The key to addressing these challenges is to directly visualize these emergent quantum at the atomic scale. Combining beyond state-of-the-art scanning tunnelling microscopy (STM) under magnetic fields and ultra-low temperatures, you will aim to detect the novel emergent quantum phases in KAMs, such as the AV3Sb5 (A = K, Rb and Cs) kagome metal and the R166 kagome magnet. Your focus will start from the electronic liquid crystal phases, then look into the topological phases, and finally investigate the mechanisms of the exotic charge density wave. You will explore the connections of these quantum states to other modern quantum matter such as Weyl semimetals, topological magnets, and topological superconductors. These efforts will significantly expand our knowledge of quantum matter physics in recently discovered quantum materials, advancing the field of condensed matter physics.

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