Maxime Dion obtains his PhD

Maxime Dion reached a major milestone on Monday, September 11, 2017, when he successfully defended his PhD thesis. And while this step wasn’t always easy, the doctoral student could navigate in familiar territory. Université de Sherbrooke is a bit like home to Maxime, who came for a bachelor’s degree in physics and ended up staying until the end of his PhD.

“It’s neither the end, nor the beginning—it’s a step I’m taking that’s part of a certain continuity. Even though the process hasn’t always been easy and it took me a while to get promising results, it’s still a wonderful opportunity to showcase elements we have developed during my doctorate degree.” In keeping with the theme of continuity, Maxime is joining the Institut quantique team as a research professional.

Why Sherbrooke?

“I wasn’t crazy about the idea of moving to a bigger city, so I followed in my brother’s footsteps who was studying engineering here.” But if Maxime stayed in Sherbrooke, it was because of his passion for physics. In the Department of Physics at Université de Sherbrooke, Maxime found an environment in which he could flourish intellectually. “I love the collegiality here. It’s an amazing learning and working environment. It promotes discussions and fosters collaborations. We have a lot of freedom.” Maxime had, among other things, the opportunity to teach on several occasions and to collaborate with Professor Louis Taillefer and Professor André-Marie Tremblay’s groups during his studies.

When he’s not in the lab, Maxime can usually be found on his bike. “The area around Sherbrooke has some outstanding roads and countryside, and no shortage of hills! Cycling lets me clear my mind after a day full of equations, samples, measuring instruments, etc.”

THE SUBJECT OF HIS THESIS

Here’s a summary of what Maxime Dion presented to the jury on September 11: “The main subject of my dissertation is the study of charge transfer at the interface between two superconducting cuprates of opposite doping. I have experimentally demonstrated that this charge transfer causes the appearance of an insulating zone at the interface between these two materials that we call the “Mott plateau.” This phenomenon was first theoretically predicted by the work of Maxime Charlebois, a student in Professor Tremblay’s group. Maxime’s thesis therefore represents the culmination of a purely Sherbrooke-based collaboration between two groups covering both the theoretical and experimental aspects of this project.

“My dissertation is part of a recent effort to fabricate electronic devices using non-conventional materials. Today’s microelectronics industry relies almost exclusively on silicon. The microfabrication techniques of this material have been developed over more than half a century with the remarkable results that we see today. We are now trying to adapt these techniques to another family of materials: oxides. Our long-term goal is to create devices with previously unseen properties.”

“Maxime’s thesis explores another way of studying the properties of materials with odd physical behaviours,” explains Professor Fournier, Maxime’s supervisor. “Usually we apply strong magnetic fields to them and cool them to a very low temperature where we dope them with impurities to affect their superconductivity and other physical properties. In this dissertation, Maxime uses a proximity effect similar to what is produced with semiconductors by inducing an insulating interface layer between two superconductors. It’s completely counter-intuitive, but it allows us to deepen our understanding of cuprates and manipulate them to understand how electrons form new phases that are full of surprises. This is the quantum playground of Maxime and his colleagues!”

The Future

The PhD candidate has already embarked on a career as a research professional at the Institut quantique and the future looks promising. “The fact that in one location we have the facilities to create materials from atoms, microfabricate them and characterize them makes Sherbrooke an excellent place to make amazing discoveries. My goal is for the members of the institute to build on my experience with the fabrication and characterization techniques applied, in particular, to the non-conventional materials that I worked on in Professor Patrick Fournier’s lab. We’re starting to look at applications that use these new materials in the form of devices. My role will be to see how we can adapt the fabrication techniques to achieve our objectives.”

Some exciting challenges ahead.