Experimental or theoretical physics?

By Guest Blogger: Bristol and Bath CDT-CMP on June 20, 2016

Output from a simulation for my Masters project at Glasgow University. Copyright Emma Gilroy 2016. All rights reserved.

Like every undergraduate physicist I started out doing lab work at least once a week. All these had a work sheet we had to follow and were heavily experimental. Honestly, I didn’t really enjoy them all that much but as I progressed though my degree I was able to choose what I wanted to work on. By the time I started my Masters project I was only interested in theoretical projects. I really enjoyed them. I loved creating simulations and I knew when something went wrong it was something I’d done. And you always got some lovely looking data! (If you compare the first 2 images in the post you will see what I mean!)

Then came the time to decide what to do with my life. I knew I wanted to pursue a PhD so I started applying to various universities. Unsurprisingly, four out of the five projects focused on computational simulations. However, I picked the only one which had an experimental element, the Condensed Matter Physics CDT in Bristol and Bath. I had fallen in love with Condensed Matter Physics (CMP), especially magnetism, by the end of my Masters and I wanted to understand it better. I wanted to be able to read papers and know how the experimental techniques worked and how this related to their results and impacted my potential future research.

Experimental data from my first project in the CMP-CDT. Copyright Emma Gilroy 2016. All rights reserved.

My plan was to try everything and learn as much as I could in the first year, then I would choose a theoretical PhD project. I picked a wide variety of Physics Techniques modules (short introductory training modules into a range of techniques important in CMP) so I could try lots of new and interesting things. I got to use the clean room at Bath, design and etch circuit boards, use an electron microscope as well as a variety of other things. For my first longer research project in the CDT I decided to stick with something I felt comfortable with. I was looking at magnetic proximity effects from iron in uranium. The theory was something I had a little knowledge about so I had no idea what to expect from the experimental side. I had to learn how to attach 25 micrometer diameter gold wire from a contact pad to the sample we were looking at. It was fiddly and frustrating, very frustrating! And then there were the actual magneto-resistance measurements… These consisted of turning on a current source to create a magnetic field, then waiting 20 minutes and pressing a button to take the field back to zero, then another 20 minutes and switching the polarity of the field…and so on. Each measurement took close to an hour and a half to complete where we just had to sit and wait in order to press one button! However, some of the results were very interesting, which made the whole thing worth it in the end.

Somehow, even with all the things that frustrated me I chose to stick with experimental physics a little while longer. I took on a placement with one of the Partners of the CDT-CMP in Nijmegen at the High Field Magnet Laboratory. I got to learn how to create a working experimental probe and how to take low temperature measurements. The more I did it the more I enjoyed it.

Then just at the end of February we were given the list of potential PhD project choices. Would you believe it? – I decided to continue with my first long research project in the CDT. All the labs and projects I did throughout the year really opened my eyes to what experimental physics was really like. Yes, there was a lot of waiting around and different bits and pieces were always breaking down but it was a lot of fun! It is so rewarding when you spend a long time preparing your measurements and then they finally work; I can’t wait to see where my PhD takes me and what other skills I will end up learning by taking on an experimental project. Maybe, I’ll even be able to use some of the skills learned in my theoretical adventures to make my PhD as interesting as possible.