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Viliam Vaňo defended his doctoral thesis entitled “Designing quantum matter in two dimensions” successfully in June 2023 and subsequently graduated from the Department of Applied Physics- this year in March, Vaňo was selected for an Aalto thesis award recognizing his outstanding thesis work published in five highly acclaimed articles, two of those in Nature. In this article Vaňo reflects on his scientific work and overall experience as a doctoral student in the Atomic Scale Physics group led by Prof. Peter Liljeroth.

New discoveries

On the technical side, the team of Liljeroth use a scanning tunnelling microscope (STM) to study many-body quantum phenomena in two-dimensional samples. STM is capable of imaging a sample and probing its electronic structure, both with an atomic resolution. The team uses molecular-beam epitaxy to synthesize various two-dimensional, so-called van-der-Waals (vdW) materials and their heterostructures and subsequently, probes their electronic properties using STM.

The phenomena uncovered in this way are otherwise difficult to find in naturally occurring materials. Vaňo himself points out that the difference between studying single-body and many-body physics like he did is comparable to the difference between studying a single human’s behaviour versus studying a whole society. Depending on the conditions, different exciting phenomena can arise. 

Using these techniques, Vaňo made new discoveries in the field of quantum materials. The highlight was a first author paper in Nature entitled “” resulting from a project he initiated. The paper presents breakthrough results on how van der Waals heterostructures can be used to engineer heavy-fermion physics using specifically designed model systems. These results open up an essentially new topic in the field of quantum materials. “Quantum materials provide the building blocks and ultimately, the discovery of new phenomena in quantum materials allows for new forms of quantum technologies” comments Peter Liljeroth. 

Vaňo’s thesis opponent, Prof. Ronny Thomale of Würzburg University in Germany, could not agree more and also remarked on the lively discussion he has held with Vaňo during the defence which included not only experimental, but also theoretical concepts which is not directly Vaňo’s field of expertise. He also remarked positively on the outstanding research environment provided by the research group of Peter Liljeroth.

Ingredients for success

From Vaňo’s perspective, several conditions came together that allowed him to flourish during his doctoral studies. Firstly, he acknowledges Liljeroth always encouraged scientists to experiment and collaborate with others- “the lab was full of motivated young researchers”. Liljeroth was always supportive and did his best to facilitate excellent science by offering freedom to explore. “People in the team were not restricted to work on specific topics, instead, creativity was celebrated” elaborates Vaňo further. He also stresses that from the beginning of his studies, he was encouraged to work on an array of different topics that included quantum spin liquids, Mott insulators, unconventional superconductors, topological superconductivity, heavy fermions, the interplay between magnetism and superconductivity as well as ferroelectricity and multiferroicity. As a result, Vaňo himself became involved in multiple collaborations with other groups at the Department, namely the group of Profs. Adam Foster and Jose Lado. The collaborations proved very fruitful indeed. Vaňo comments that people involved in those collaborations always responded fast, were enthusiastic and open-minded. Specifically, “it was the brainstorming with Lado that led to the most important result of my PhD, which we published in Nature”.

Reflections on graduate student life

Outside of the University environment, Vaňo managed to sustain a good work-life balance and enjoyed many free time activities with friends and colleagues. These ranged from simply hanging out together, but also playing board games, going together to a cottage, and sports such as climbing, kayaking, skating, curling and many more. “All of this helped me to keep me motivated and prevent me from burning out, like many people in academia do” adds Vaňo.

“I truly enjoyed what I was doing and learning new things”. When it comes to giving his tips to anybody starting their doctoral studies, Vaňo has the following advice: “I would really say that they should enjoy it and not overwork. I really do think they should not only focus on getting results but on enjoying the process of what they’re doing”. Following his graduation, Vaňo is currently a Princeton Center for Complex Materials Postdoctoral Research Fellow working in the group of Prof. Ali Yazdani.

More resources: 

Link to Viliam Vaňo's doctoral thesis