Research Projects

The topological behavior of electrons and its observable consequences have been among the most intensively researched topics in modern condensed matter physics and materials science. The topology of electrons is embedded in the geometric properties of electron states, more precisely in their “Berry curvature” in reciprocal space. Materials exhibiting such behavior are classified as topological materials. While the topological behavior of electrons has continued to be studied over the past decades, less is known about the influence of electronic topology on non-electronic particles, particularly bosons such as magnons, phonons, and plasmons. These are quasiparticles arising from the collective excitations of a many-body system. In this project, we aim to investigate this unexplored question: How does the topology of electrons affect the behavior of bosons when they interact with electrons? Although the Berry curvature of phonons and magnons has received considerable attention in recent years, one aspect that has received little attention so far is the interplay between the Berry curvature of electrons and that of bosonic quasiparticles. Here, we intend to explore this avenue by first developing a theoretical framework to calculate the Berry curvature of phonons, magnons, and plasmons in systems where they interact with topological electrons. This task presents different challenges for phonons, magnons, and plasmons. In particular, the Berry curvature of plasmons is a novel quantity for which existing research is extremely limited. The developed framework will then be used to study the observable consequences, focusing on non-trivial transport properties. For example, transverse transport phenomena such as the Nernst effect, spin Nernst effect, and thermal Hall effects will be investigated thoroughly. Investigating these transport properties is important, as these bosons also carry information and can thus be explored for electronics analogs in insulators—specifically, topological phononics, magnonics, and plasmonics. This project involves the development of novel and original formalisms that will have implications beyond this work, including in fields such as spintronics and topological quantum computation.