Meet members of the group and hear about our research at the following contributions at the APS March meeting in Anaheim:
Applications for the 2025 entry are open!
Interested in an exciting PhD project working with cutting-edge instrumentation in a stimulating environment and combining advanced experiments, development of bespoke instrumentation, complex data analysis and numerical modelling of quantum materials? We are currently searching for outstanding candidates who are seeking to pursue a PhD on a funded scholarship. You can find a list of example projects on the web page of the School of Physics and Astronomy.
Our group develops and operates cutting edge instrumentation for atomic scale studies of electronic structure, complex magnetic orders and unconventional superconductivity in quantum materials. The experiments are undertaken in dedicated ultra-low vibration labs. Projects are embedded in the Centre for Designer Quantum Materials, offering a vibrant and stimulating environment. Our work is highly collaborative, and usually we combine characterisation by multiple techniques with advanced numerical modelling using calcQPI.
If you have any questions, do not hesitate to get in touch. Submit applications through the University portal.
Last year we posted a preprint (arxiv, now published in Phys. Rev. Mat.) in which Luke suggested that it should be possible to stabilise the high-pressure superconductivity seen in La3Ni2O7 in thin films at ambient pressure by exploiting epitaxial strain (see figure on the right), informed by Density Functional Theory calculations. Harold Hwang and collaborators have now reported evidence for ambient pressure superconductivity in strained thin films of La3Ni2O7 (with independent confirmation from the group of Qi-kun Xue and Zhuoyu Chen)! Besides being exciting in its own right, the work opens up the possibility to study the gap structure by STM, QPI and ARPES to resolve the symmetry of the order parameter and pairing mechanism.
When Diracula gets rotten teeth 🎃 Van Hove singularities appear – read in our new paper, how to engineer sharper teeth through higher order Van Hove singularities. Congratulations to Kong, Vlad, Evgenia, Becca, and Siri for winning the Halloween pumpkin competition of the School!
Admittedly, the analogy has its flaws as it is blunter teeth in k-space that result in sharper Van Hove singularities …
Full reference:
A. Chandrasekaran, L.C. Rhodes, E.A. Morales, C.A. Marques, P.D.C. King, P. Wahl, and J.J. Betouras, On the engineering of higher-order Van Hove singularities in two dimensions, Nat. Commun. 15, 9521 (2024).
Our paper on how small structural distortions affect superconductivity in Sr2RuO4 is out. Our results not only explain why the surface of this material is not superconducting, but also how to optimise Tc (so, hey, if you want to make a room temperature superconductor, read our paper! – though still a bit to go). Surprisingly, the phase diagram is quite different dependent on which method one uses to obtain the pairing instability. Using the superconducting order parameters predicted from RPA and FRG, we show how to detect the symmetry of the order parameter in quasi-particle interference using the phase-referenced Fourier transformation.
The St Andrews part was led by Luke, with QPI calculations by Rebecca and Carolina. Great collaboration with Jonas Profe (FRG, Frankfurt) and Matteo Dürrnagel (RPA, Würzburg/Zürich).
Full reference:
Jonas B. Profe, Luke C. Rhodes, Matteo Dürrnagel, Rebecca Bisset, Carolina A. Marques, Shun Chi, Tilman Schwemmer, Ronny Thomale, Dante M. Kennes, Chris Hooley, and Peter Wahl, Magic angle of Sr2RuO4: Optimizing correlation-driven superconductivity, Phys. Rev. Research 6, 043057 (2024).
How does a doped Mott insulator avoid becoming metallic? See our new paper in Nature Communications on the surface of the hidden Mott insulator PdCrO2. The surface polarity results in clean doping, yet the system remains insulating. Hidden gem: the local order that prevents metallicity is highly degenerate with local disorder, see below the movie of its dynamics after a voltage pulse. Great collaboration with Phil King’s group and researchers at TDLI, CNR SPIN and the MPI for the Chemical Physics of Solids.
Full reference:
Chi Ming Yim, Gesa-R. Siemann, Srdjan Stavrić, Seunghyun Khim, Izidor Benedičič, Philip A. E. Murgatroyd, Tommaso Antonelli, Matthew D. Watson, Andrew P. Mackenzie, Silvia Picozzi, Phil D.C. King, and Peter Wahl, Avoided metallicity in a hole-doped Mott insulator on a triangular lattice, Nat. Commun. 15, 8098 (2024), arxiv/2311.17139.
Congratulations to Olivia and Dylan to their graduation!
Olivia graduated with her PhD thesis “Scanning Tunnelling Microscopy of Magnetic van der Waals Materials” and set up our STM4, which enables imaging of electronic states in thin films grown by molecular beam epitaxy and produces amazing data.
Dylan obtained his Master in Theoretical Physics with a final year project in which he modelled electronic states in twisted bilayer graphene. For his work, he was awarded the prize for the best final year Theoretical Physics project and received the fifth year medal for theoretical physics.
Have you heard of the magic angle of Sr2RuO4? No? Read in our new preprint how small structural distortions affect superconductivity in Sr2RuO4. Our results not only explain why the surface is not superconducting, but also how to optimise Tc. Surprisingly, the phase diagram is quite different dependent on which method one uses to obtain the pairing instability. Using the superconducting order parameters predicted from RPA and FRG, we show how to detect the symmetry of the order parameter in quasi-particle interference.
The St Andrews part was led by Luke, with QPI calculations by Rebecca and Carolina. Great collaboration with Jonas Profe (FRG, Frankfurt) and Matteo Dürrnagel (RPA, Würzburg/Zürich).
Full reference:
Jonas B. Profe, Luke C. Rhodes, Matteo Dürrnagel, Rebecca Bisset, Carolina A. Marques, Shun Chi, Tilman Schwemmer, Ronny Thomale, Dante M. Kennes, Chris Hooley, and Peter Wahl, The magic angle of Sr2RuO4: optimizing correlation-driven superconductivity, arxiv/2405.14926.
Submit your abstract now for minicolloquium 42 “A quantum leap: unraveling the mysteries of correlated electronic states in quantum materials through atomic-scale imaging and spectroscopy” at the CMD conference in Braga, Portugal, and join us for lively discussions about new insights from atomic-scale imaging of correlated states.
See here for a list of confirmed invited speakers.
How can the magnetization direction in a ferromagnet drive a Lifshitz transition? In our new study of Sr4Ru3O10 with QPI and ARPES we establish its low energy electronic structure and propose a tight-binding model that captures the key features, including the spin- and orbital character of the van Hove singularity closest to the Fermi energy. Using this model, we identify a mechanism for a Lifshitz transition that is based on the magnetization direction and spin-orbit coupling.
Reaching those conclusions was only possible by combing the millikelvin QPI results measured by Carolina and Weronika with DFT modelling from Luke and ARPES done in collaboration with Phil Murgatroyd and Phil King’s group.
Original publication:
