2024 in review and outlook for 2025

2024 Retrospective

I joined the group of Prof. Simon Bending at the University of Bath in July 2023. Since that time, one of the things I have been working on is exploring the unusual coexistence of ferromagnetism and superconductivity in the iron-based superconductor EuFe\(_2\)(As\(_{1-x}\)P\(_x\))\(_2\). With samples kindly provided by Prof. Tsuyoshi Tamegai, The University of Tokyo, I performed systematic measurements of magnetisation and magnetic relaxation, focusing particularly in the region of the ferromagnetic ordering temperature. From these measurements, we found some very intriguing behaviour in the dynamics of the superconducting vortices that seemed to correlate strongly with the onset of the ferromagnetic order.

At the start of 2024, we were fortunate to be able to explore this behaviour further by establishing a valuable collaboration with the group of Prof. Martino Poggio. His group specialises in making very sensitive magnetic force microscopy measurements, which is ideal for visualing this unsual behaviour. The measurements revealed yet further interesting physics which led us to the identification of a novel interaction between superconducting vortices and ferromagnetic domains - the vortex polaron - the behaviour of which has been elucidated through theoretical description from the group of Prof. Alexandre Buzin, University of Bordeaux.

To me, this project has been very much a textbook example of academic collaboration, with important contributions coming from a multitude of parties, and with the final combined result being elevated above the sum of its parts. Once it felt that we had gathered all of the requisite pieces of the story, the final task was to bring them together for publication. Given the number of contributing parts, this was not a straightforward task and took quite a number of iterations until we were satisfied with our work. While we did not quite get our results published before the end of 2024, the process is well under way and a preprint of the manuscript can be found here in the meantime.

In 2024, we have had two new PhD students join the group. Both have made a good start on their projects and it will be great to see how things pan out over the next year.

I was also fortunate to attend the 2024 APS March Meeting in Minneapolis, USA, as well as the CMQM meeting in St. Andrews, Scotland.

Plans for 2025

I am very much looking forward to attending the IBS2app 2025 conference in Miyazaki, Japan, where I will be presenting the research (mentioned above) on vortex dynamics in EuFe\(_2\)(As\(_{1-x}\)P\(_x\))\(_2\). I have never been to Japan but it is always somewhere I have wanted to visit. To say I am excited would be an understatement.

We currently have a number of other ongoing projects that look as if they may bear some interesting fruit, though I cannot say more for now. There are also some older results that never quite got the love they deserved at the time, and so I hope to make 2025 a year to finally finish off some outstanding projects!