Matthew Watson

I use the technique of Angle-Resolved Photoemission Spectroscopy (ARPES) to investigate the electronic structure of quantum materials. At I05 at Diamond, I am particularly involved with the push towards ever smaller beam size at the nano-ARPES endstation, as the demand increases for ARPES measurements from inside small domains, on thin flakes, and even from in-operando devices.

One of my research interests is correlated electron systems, with a particular focus on the Fe-based superconductors such as FeSe. I have performed and analysed a number of ARPES experiments with extremely high energy resolution in order to probe both the temperature-dependent electronic structure and the superconducting gap. As part of this, I also performed ARPES measurements of samples under mechanical strain to overcome issues with domains.  

More recently, I have been working on understanding phase transitions in a number of layered or quasi-2D materials, including transition-metal dichalcogenides, for example taking a fresh look at the well-known charge density wave in TiSe₂ in both bulk and monolayer forms.    

Another ongoing research project is on van der Waals ferromagnets (e.g. CrSBr and CrGeTe₃), and how ARPES can shed light on the superexchange mechanism in this family of materials. 

I do my own DFT calculations to support the experimental work and take an interest in tight-binding-based approaches to modelling electronic structure. I also maintain an interest in transport measurements and soft x-ray techniques such as XMCD, where these are complementary to the ARPES studies. 

Please visit my researchgate profile , my ORCiD or my Google Scholar page to view my latest publications and a complete list.

Some personal highlight from my research at Diamond are:

Phys. Rev. B 110, L121121 (2024)

npj 2D Materials and Applications  8, 54 (2024)

Nature Communications 14, 3388 (2023)

Phys. Rev. B 103, 155105 (2021)
Phys. Rev. Lett. 122, 076404 (2019)
npj Quantum Materials. 4, 36 (2019)

Phys. Rev. B 97, 035134 (2018)

Phys. Rev. B 98, 180503(R)

New J. Phys. 19 103021 (2017)
 

Back in 2010-11 in my final year of my undergraduate at Oxford, I undertook a Master’s project with Amalia Coldea, looking for quantum oscillations in LiFeAs – a member of the Fe-based superconductor family, and a very hot topic at the time. I was attracted to the idea of carrying on research in this direction, and so I started my DPhil in 2011. Most of my DPhil was spent performing measurements in high magnetic fields both in the Clarendon laboratory and at international facilities. However in the last year of my DPhil, new and improved crystals of FeSe became available at the same time that the I05 beamline at Diamond was just becoming available to users to perform ARPES measurements. This happy coincidence led to my first steps in ARPES,  the start of my collaboration with my now-colleague Timur Kim, a much-cited paper and a big chunk of my thesis.

As I came to leave Oxford, the opportunity arose to take on a postdoc role at Diamond in 2015, where I continued to work on Fe-based superconductors as well as expanding into other topics and starting to develop a fuller understanding of synchrotron ARPES. This led to a second postdoc in the group of Phil King at the University of St Andrews from 2017-19, during which time I undertook several beamtimes at other European facilities and started to develop research interest into 2D materials and charge density wave systems. 

I returned to Diamond in 2019 as a beamline scientist at I05. In my current role I support the experiments of groups from around the world who come to our facility, and maintain and develop the equipment to keep it world-leading, with particular responsibility for the nano-ARPES branch. I supervise joint PhD students who spend some of their time at Diamond, as well as helping Diamond-based postdocs in their research. 

.