We are pleased to announce that Dr. Gonzalo Alvarez-Perez has won the Materials 2024 Best PhD Thesis Award. As a winner he will receive CHF 800 and a free voucher for article processing fees valid for one year in Materials (IF: 3.2, ISSN: 1996-1944).

Dr. Gonzalo Álvarez-Pérez completed his PhD in condensed matter physics, nanoscience, and biophysics at the University of Oviedo, Spain, where he investigated the interaction between mid-infrared light and strongly anisotropic two-dimensional materials under the supervision of Dr. Pablo Alonso-González and Dr. Alexey Nikitin. His thesis received multiple national and international distinctions, including the 2024 Best Experimental Thesis Award from the Condensed Matter Division of the Spanish Royal Physical Society, and was selected for publication in the Springer Theses series. During his PhD, he completed research stays at Columbia University (New York, USA) in Prof. Dmitri Basov’s lab through a Fulbright Fellowship and at the Fritz Haber Institute of the Max Planck Society (Berlin, Germany) in Dr. Alexander Paarmann’s lab. He is currently a postdoctoral researcher at the Italian Institute of Technology (Lecce, Italy) in Dr. Cristian Ciracì’s lab, where he explores nonlocal nonlinearities and hydrodynamic effects in semiconductors for all-optical neuromorphic computing. In 2026, he will begin his independent research program, supported by a Marie Skłodowska-Curie Postdoctoral Fellowship.

The following is an interview with Dr. Gonzalo Alvarez-Perez:

My doctoral research explored how light behaves at the nanometer scale, where reality is governed by the counterintuitive principles of quantum mechanics. Studying physics in these dimensions, which are comparable to atoms and molecules and about 10,000 times thinner than a human hair, is not only interesting in itself but also enables the design of materials and devices that harness quantum effects for new functionalities. This lies at the heart of nanotechnology. However, controlling light at such tiny scales remains a fundamental challenge due to the diffraction limit, which prevents conventional optics from focusing light to regions smaller than roughly half its wavelength. In essence, light and the nanoscale are two domains that are difficult to reconcile. That is why we cannot see individual molecules or atoms with our eyes or standard optical microscopes. To overcome this barrier, scientists have developed alternative approaches. One of the most promising involves polaritons, which arise from the coupling between light and matter. They can be pictured as waves on the surface of the sea, created by the interaction between air and water. In a similar way, polaritons are electromagnetic waves—essentially light waves—traveling along the surface of materials. Because of this hybrid nature, their properties depend strongly on the material itself. This matter component not only allows light to be confined to dimensions far smaller than the diffraction limit but also enables the tuning of its behavior through the choice of material. In atomically thin materials such as graphene, these effects become even more pronounced, opening new avenues for manipulating light at the nanoscale. Beyond graphene, thousands of other two-dimensional materials exhibit diverse optical responses, including strong anisotropy, that allow for directional guiding and control of light. In my thesis, we established the fundamental principles underlying hyperbolic phenomena such as anomalous refraction and negative reflection; uncovered new mechanisms for polariton propagation and interaction, such as stacking and twisting these layers; and proposed strategies for their active control, like gating and applying gate voltages.

I don’t think it’s very meaningful to divide doctoral graduates, or people in general, into “outstanding” and “not outstanding”. Reality is rarely that binary. Success in a PhD, as in life, depends on many factors beyond individual talent, such as mentorship, timing, and even luck. What truly matters, I believe, is curiosity and having critical sense and the willingness to question assumptions, including one’s own.

My current research focuses on the mid-infrared spectral range. This region has a lot of potential for chemical sensing, thermal management, and on-chip optical communications but still faces challenges when it comes to developing those technologies. These range from the difficulty of finding industry-compatible materials for photonics to the difficulty of integrating efficient on-chip sources and detectors. Still, the field is moving fast: highly anisotropic polaritons, as we discussed before, now enable deep subwavelength, low-loss light and directional propagation. People have also developed record Q-integrated resonators in the mid-IR. Quantum cascade lasers and optical parametric amplifiers provide good-quality mid-infrared sources that we didn’t have decades ago. Achieving active tunability and strong nonlinear optical responses remains another big obstacle. In my postdoctoral work I’m studying nonlinearities that arise from non-local electron interactions in doped semiconductors. These effects are naturally strong, tunable, and ultrafast, offering a powerful method to control light at the nanoscale, with some potential for signal processing and optical AI.

Absolutely. Technological progress has completely changed what’s possible in this field. Advances in laser sources—such as optical parametric oscillators, quantum cascade and free-electron lasers, and ultrafast systems—together with high-sensitivity detectors have transformed our ability to study materials in the mid-infrared. At the same time, techniques like scattering-type near-field microscopy, even under cryogenic or magneto-cryogenic conditions, and the complementary progress in electron microscopy and electron energy-loss spectroscopy now let us probe optical modes and electronic excitations with incredible control and resolution, both in time and space, and directly correlate them with structural and chemical features. In parallel, high-quality semiconductor growth by molecular beam epitaxy and improved 2D material fabrication methods, from exfoliation and transfer to chemical growth, have opened the door to exploring light–matter interactions, polaritonic behavior, and collective electronic effects that were simply out of reach a few years ago.

There’s no single path to doing science. At its heart, science is driven by curiosity, by the genuine desire to understand how things work. My advice would be to stay true to that curiosity. The reality of academia today can make it difficult, as success is often measured through publications, awards, and metrics like the h-index. It’s a system we are all pushed to navigate, but it shouldn’t define you. Learn to use it strategically: publish, seek funding, build visibility—but always in service of the questions that truly excite you. And, whenever possible, contribute to reshaping the culture toward something that values meaning and discovery over mere performance.

When choosing a journal, I prioritize its scientific reputation and rigor. Unfortunately, prestige still matters a lot, especially early in one’s career, when visibility can determine future opportunities. What I consciously avoid are predatory or low-quality journals, both as an author and as a reviewer. Regarding open access journals like Materials, I think the idea is good (knowledge should be accessible) but too often the model is driven more by profit than by scientific value. Open access only makes sense if it maintains high editorial standards and real peer review; otherwise, it just becomes another symptom of a broken system that confuses quantity with quality.

It’s a modest award, but it still feels nice to be recognized; we all appreciate a bit of validation. For me, it’s especially meaningful because I’ve heard that young researchers are finding the thesis useful and accessible. That was one of my main goals: to write the kind of text I would have liked to read when I started my PhD. This wouldn’t have been possible without my supervisors, Dr. Pablo Alonso-González and Dr. Alexey Nikitin, who have been exceptional mentors, both scientifically and personally. I’m also deeply grateful to everyone who contributed along the way: colleagues from Alex Paarmann’s group at the Max Planck Institute in Berlin, Josh Caldwell’s lab at Vanderbilt, Dmitri Basov’s group at Columbia University, Susanne Kehr’s group at TU Dresden, and many others. And, of course, to my closest ones, who have always taught me, supported me, and created the conditions for everything else to happen, they’re the ones who really deserve an award.