From mid-July until the beginning of October, I spent nine weeks working with the Quantum Matter group in the Department of Physics, University of Cambridge. My project involves growing yttrium-based cuprates (YBa2Cu3O6+δ, often abbreviated as YBCO, where δ represents the doping levels) crystals, which act as superconductors at high critical temperatures. I have also acquired various skills required when preparing the samples for measurements, such as pressure and strain samples, transport property, as well as physical and magnetic properties at strong magnetic fields. The doping in the crystals is dependent upon the temperature, pressure and time under which they are annealed. This in turn influences the critical temperature under which the crystals will exhibit superconducting properties.
I was also deeply involved in the group meetings held every week, where group members report on their progress. It was interesting to learn what the rest of the group has been working on (they focus on Kondo insulators, which are alloys that display increasing resistance at temperatures lower than a critical temperature). My mentor for the project guided me very well throughout the summer. We had fascinating discussions on the theory of superconductivity and the equations governing them, as well as their limitations in explaining the ‘strange metal’ region of the phase diagram for YBCO.
The placement was a very rewarding and meaningful experience and gave me an insight into career prospects for physics in academia. I am looking forwards to growing other rare earth cuprates (Dysprosium and Europium based) and mapping their phase diagrams to investigate superconducting behaviours as a term-time project.
Hui Taou Kok
Undergraduate student, Natural Sciences