Tracking and Manipulating Band Properties in Materials via Light–Matter Interaction
Prof. Dr. Michael Schüler
Université de Fribourg, Paul Scherrer Institut: group leader
https://sites.google.com/view/schueler-research-group/home
16:15 - 17:15 Tuesday 17 June 2025 HS 05.01 The quantum geometry of Bloch electrons — describing the momentum-space structure of electronic wave-functions — plays a critical role in determining material properties, especially in transport phenomena and light–matter interactions. However, directly accessing this geometry remains a significant experimental challenge. If we could dynamically control these properties, we could achieve ultrafast manipulation of topological phases and functionalities in solids.
In this talk, I will show how light–matter coupling provides powerful means to probe and control the orbital textures of electrons in solids. We begin with angle-resolved photoemission spectroscopy (ARPES), a widely used technique to map electronic band structures. Despite its apparent limitations, ARPES contains hidden information about the underlying wave-functions due to the coherent nature of the photoemission process. Recent advances in first-principles modeling now allow us to decode this information, revealing quantum geometric features such as orbital angular momentum. I will highlight our results in chiral materials, where these effects have direct relevance for emerging orbitronics applications.
Going beyond probing, I will then turn to Floquet engineering — a method to modify material properties by exposing them to periodic driving with laser light. This approach enables the design of effective Hamiltonians with tailored quantum geometry, offering a route to dynamically controlling electronic states. I will present recent computational and experimental progress in realizing Floquet-engineered phases in materials such as black phosphorus and graphene, showcasing the potential of this approach for next-generation quantum materials control
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