Jennifer Graham wins the Don McKenzie Paul Thesis Prize 2025
Jennifer Graham, former PhD student at the ILL and Birmingham University and currently at PSI, has been awarded this year’sprize for her “ground-breaking contributions to the study of frustrated magnets using neutron polarisation analysis combined with novel data analysis methodologies, and especially her discovery of a spiral spin liquid phase in LiYbO2.”
The award was officially announced today, 18 March 2025, at the UK Neutron and Muon Science and User Meeting (NMSUM) by Ross Stewart (Institute of Physics/Royal Society of Chemistry, Neutron Scattering Group Chair). Jennifer Graham will deliver her Prize lecture at the Theoretical and Experimental Magnetism Meeting (TEMM) 2025, taking place in Abingdon, Oxfordshire (UK) on 23-24 June.
Jennifer Graham developed her PhD work at the ILL and Birmingham University, under the supervision of Andrew Wildes (ILL) and Lucy Clark (Birmingham University). She successfully defended her thesis, entitled ‘Magneto-structural correlations and the role of disorder in frustrated magnets’, in July 2023.
Her thesis work, published in Physical Review Letters, addresses the role played by structural disorder in driving the physics in quantum spin liquid candidate compounds - a central question in quantum magnetism. It further reveals a model compound to study the physics of an exotic quantum state. In her work, Jennifer Graham made extensive use of neutron and synchrotron scattering experiments in characterising and quantifying the magnetic and atomic structure of three compounds.
Jennifer Graham has been nominated for the Prize by Wildes, who highlighing the “remarkable depth of understanding and intuition, supported by an excellent work ethic” and stresses that Graham “led the research effort on the compound and deserves the acknowledgement and credit for the discovery.”
The compound LiYbO2 has a distorted diamond lattice, and was proposed to host an exotic magnetic state known as a spiral spin liquid. Wildes recalls that Graham “realised that LiYbO2 warranted special attention and convinced us to perform experiments.” She employed neutron powder diffraction to provide a careful characterisation of the nuclear and magnetic long-ranged structures and neutron diffuse scattering with polarisation analysis to search for magnetic disorder.
Her work proved that LiYbO2 indeed hosts a spiral spin liquid state, and is the first such compound shown to have one. The magnetic structure turned out to be rather complex, and the data analysis to characterise it was extremely challenging and at a frontier of modern structure refinement techniques. Graham was able to employ an innovative and novel methodology to analyse the data, combining Rietveld analysis and Reverse Monte-Carlo to provide a comprehensive, quantitative, and self-consistent model for the magnetic structure.
The Don McKenzie Paul Thesis Prize is awarded biennially by the UK Neutron Scattering Group, recognising an outstanding PhD thesis in which the use or development of neutron scattering is instrumental in addressing a current scientific challenge. The prize is named in honour of Don McKenzie Paul (1953 – 2019), a leading condensed matter scientist and professor at the University of Warwick.
Andrew Goodwin (Oxford University) supported Jennifer Graham’s nomination, highlighting “three key components of her thesis”: her groundbreaking discovery of a spiral spin liquid phase in LiYbO2; the exploration of the interplay between compositional and magnetic disorder in the honeycomb layered material Mn0.5Fe0.5PS3 using polarised neutron scattering measurements and complex computational analysis; and the study exploiting microwave synthesis to access high-quality samples of ZnV2O4, shedding new light on the role of sample variation in explaining inconsistencies in the literature. The idea that microwave synthesis might provide better samples than conventional approaches “is revolutionary, and will find many applications across the quantum materials field,” he concludes “Her work is important not only from the perspective of quantum magnetism, but also from the methodological viewpoint of interpreting magnetic diffuse scattering.”
Read about Jennifer's work in our webstory "Upward spiral for next-generation computing" which explains how the experimental evidence of rare magnetic behaviour in LiYbO2 will help to open the door to a new family of materials with potential applications in spintronics, quantum computing and more.
Andrew Wildes and Jennifer Graham at the Panthéon in Paris – paying tribute to Paul Langevin
From left - Professor Andrew Goodwin (Oxford University); Jennifer Graham (former PhD study at the ILL and Birmingham University now at PSI, ); Dr. Lucy Clark (Birmingham University) and Dr. Phoebe Allen (Birmingham University)
References:
J. N. Graham et al, Phys. Rev. Lett. 130, 166703 (2023) https://doi.org/10.1103/PhysRevLett.130.166703