Study of the emergent thermodynamics in magnetic systems

The laws of thermodynamics are a cornerstone of our understanding of nature, spanning all scales of the universe and nearly every field of physics. Magnetism, like thermodynamics, also permeates all scales—from the quantum spin of electrons with the smallest known magnetic moment (9.3·10⁻²⁴ T) to magnetars, neutron stars with the strongest measured magnetic fields (1.6·10⁹ T). It is thus not surprising that magnetic models have served as paradigmatic systems for studying thermodynamics and statistical physics.

In this thesis project, we propose to use one of the tiniest stable magnetic structures—magnetic skyrmions—as a platform to explore the interplay between mechanics and nonequilibrium thermodynamics. We will begin with simple configurations of spins and magnetic moments, studying their behavior from first principles. When stochasticity is introduced, deterministic laws no longer suffice, and probabilistic approaches must be developed. As the system scales up, thermodynamic quantities naturally emerge and must be defined to characterize it (e.g., entropy, effective temperature).

Magnetic systems—and skyrmions in particular—offer an ideal platform to study this scaling, from the atomic to the macroscopic level. Skyrmions are (a) ultimately built from atomic spins and their interactions; (b) capable of forming stable mesoscale structures (tens of nanometers) whose behavior requires effective theories beyond simple spin–spin interactions; and (c) able to assemble into skyrmions lattices, where individual skyrmions behave as interacting point particles, enabling a macroscopic description based on stochastic classical dynamics.

Tracing these different scales of description will guide the thesis. Exploring their consequences—both from thermodynamic and magnetic perspectives—will provide a comprehensive conceptual framework for the project and serve as fundamental basis for the magnetic energy-efficient devices.

The candidate should have a good background in fundamentals of Physics and on its basic laws, from Quantum theory, Electromagnetism and Thermodynamics. Some skills in computer modelling and programming are also greatly appreciated.

The candidate must be curious, adaptable, collaborative, and possess strong problem-solving skills, since the project involves several different methodologies that attacks the problem from several point of views. Proficiency in data analysis, modelling, and scientific communication will be essential for interpreting computing results. Initiative, independent learning, and teamwork are key to success in this interdisciplinary research environment.

Our research focuses on the modeling of physical systems from multiple perspectives, combining approaches that range from fundamental theory to computational simulations. The candidate will join a multidisciplinary team where modeling serves as the common language to connect diverse areas of physics.

In particular, we bring together extensive expertise in modeling magnetic systems at the nano-, micro-, and macroscales, as well as in non-equilibrium thermodynamics and the emergence of hydrodynamic behavior in heat transport. The multiple codirection of the thesis reflects the interdisciplinary nature of the project, ensuring that the student benefits from a broad range of expertise. In addition, our groups have strong backgrounds in superconducting modeling and advanced computational methods, enabling the study of systems across multiple length and time scales.

This integrated approach provides a unique framework to understand how local interactions lead to collective behavior, bridging the gap between different physical descriptions.