From Spins and Two-Dimensional Materials to Tsunamis and Tornadoes: What HSE Physicists Study

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The Laboratory for Condensed Matter Physics studies highly complex processes of interaction between molecules and atoms in solids and liquids, the quantum mechanics of these processes, and ultra-thin two-dimensional materials. HSE physicists, together with colleagues from leading academic institutes, investigate the properties of superconductors and topological materials, phenomena at ultra-low temperatures, as well as problems of turbulence and hydrodynamics.

The involvement of postgraduate and undergraduate students in research makes it possible to pass on the experience of leading specialists and to train new generations of scientists. The HSE News Service spoke with the head of the laboratory, Yuriy Makhlin, about its work.

— When was the laboratory established?

— The laboratory was founded almost ten years ago, in 2016, as the core of what soon became the Faculty of Physics. It brought together colleagues who helped to establish the faculty and who are still actively involved in its development. The idea was that students and postgraduates should be taught by actively working scientists. This significantly improves the quality of lectures and seminars and engages young people in modern science.

— How would you explain what condensed matter is and what makes it distinctive to someone unfamiliar with physics?

— It is the name of a very broad field of modern physics, partly analogous to solid-state physics. Unlike gases, in liquids and solids atoms and molecules are much closer to one another, so both their interactions and quantum phenomena play a much greater role than in gases. Taken together, these systems are called condensed matter. The term emerged in the second half of the twentieth century, when it became clear that it was reasonable to study these systems within a unified framework. Often the term is used to emphasise the significant role of quantum phenomena in such systems. These phenomena lead to very unusual properties, such as the well-known effect of superconductivity (the flow of electric current without resistance), first observed experimentally just over a hundred years ago.

— What are the main areas of work in your laboratory?

— We deal with many questions in modern condensed matter physics. Systems of small size are of particular interest; this field is often referred to as nanophysics. In particular, we study electrical transport properties, charge and spin transport in systems of superconductors, hybrid systems consisting of superconductors and normal metals, magnetics, and the physics of magnetism.

Another area is the physics of two-dimensional materials, which are extremely thin. One of the most famous such materials is graphene, for the discovery of which Konstantin Novoselov and Andre Geim were awarded the Nobel Prize in Physics. These materials possess very unusual physical properties and have a wide range of applications.

We also study quantum-coherent and topological phenomena in small systems. This area is connected, among other things, with quantum computers, quantum computing, and related technologies. We investigate the physical principles underlying their operation.

Another line of research is hydrodynamics and the physics of turbulence. The study of turbulence—that is, random chaotic flows of particles—is linked to atmospheric physics, for example to the formation of organised flows such as hurricanes and tornadoes. A closely related issue is the transmission of electromagnetic signals through the atmosphere. Turbulence can suppress signals, and it is important to describe how this happens, to understand how signal quality can be maintained, and, on the other hand, how distortions can help us study the atmosphere.

Yuriy Makhlin (right)

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— You mentioned spin—could you explain what this phenomenon is?

— In addition to charge, electrons have spin, which is often described as the electron rotating about its own axis. This property is associated with the electron’s magnetic behaviour. The field of study that explores the relationship between spin and electronic phenomena—ordinary charge currents and spin currents—is known as spintronics. The phenomena discovered in this area, for example, make it possible to control electric current conveniently by means of magnetic fields.

— Does the laboratory focus on fundamental science or applied research?

— We are primarily focused on fundamental research and on understanding the basic physical principles. One might say that we aim to understand how the world is structured. Of course, applications are expected, and applied science is responsible for developing them on the basis of these physical principles, but our priority is fundamental research.

— What about the practical results of the laboratory’s work and their application?

— To be honest, I am somewhat concerned that the focus of attention has now clearly shifted from fundamental science to applied results. Humanity has always understood the intrinsic value of the process of understanding the world—in medieval monasteries, during the Enlightenment, in the nineteenth century, and in the Soviet period—and it would be good to preserve this understanding. Without the development of fundamental knowledge, there will be no applied achievements. In our field, applied results follow directly from fundamental ones; there is no large gap between them. However, our primary task is to study the world—in our case, condensed matter physics.

— Modern science requires complex and expensive equipment. How do you address this issue?

— Our laboratory was established as a partnership with leading academic institutes: the Landau Institute for Theoretical Physics, the Kapitza Institute for Physical Problems, the Osipyan Institute of Solid State Physics, the Institute of Spectroscopy, and the Lebedev Physical Institute. We rely on the unique capabilities of our partners, which is extremely important for active research, including for young people—our students and postgraduates—who gain the opportunity to work at a modern scientific level. This collaboration is very valuable for us.

— Which divisions of HSE do you collaborate with?

— With HSE MIEM (the HSE Tikhonov Moscow Institute of Electronics and Mathematics), for example. We also share interests with the Faculty of Mathematics and collaborate with colleagues from the Faculty of Computer Science in the field of quantum informatics.

— How is cooperation with foreign scientists continuing under current circumstances?

— Naturally, certain difficulties have arisen, and institutional cooperation is limited. However, at the individual level we maintain relationships with our colleagues abroad and publish in international journals.

In recent years, we have actively collaborated with colleagues from China and India who share our research interests, and we intend to continue developing these ties.

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— What achievements of the laboratory and your colleagues make you most pleased?

— It is important that we continue to work on problems that are of interest to the scientific community; our work is recognised, and we maintain communication and collaboration with colleagues.

At first, both in Russia and abroad, colleagues were surprised that physicists were working at HSE University, but the laboratory soon became well known, and HSE’s reputation as a research university is growing.

In addition, we are pleased that we are able to actively involve young people in the work of dynamic research groups.

— How actively are students and postgraduate researchers involved in the laboratory’s work?

— We devote a great deal of effort to integrating young people—our students and postgraduates—into research activity. Over the past five years, 11 of our postgraduate students have successfully defended their theses. Most of them now work in fundamental science, including in our laboratory and in academic institutes, while some are employed in the research divisions of technology companies.

— Would you prefer to have more established scholars or young researchers in the laboratory?

— We need both. An important aspect of our work is the combination of the two, which is beneficial for both sides: leading specialists at the forefront of modern science pass on their experience, skills, and intuition to the new generation of scientists and support their academic development.

— How are the results of your research used in the teaching process?

— Our staff are active research scientists. Their high level of understanding of modern physics naturally has an impact on teaching, and it enables students and postgraduates to understand more quickly and effectively what is happening in science and to become involved in research.