Title: Optical renormalization of collective magnetic excitations in quantum materials
Speaker: Davide Bossini, University of Konstanz
Time: 2026-05-07 10：00
Venue: Room W105, Physics Building
Abstract:The advent of artificial intelligence is generating a higher-than-ever demand of data transfer, processing and storage in the cloud. Present-day data processing technology cannot be scaled up to THz frequency. It has been proposed that magnetic waves in solids, i.e. spin waves or magnons, are promising information carriers for future THz information technology with low energy dissipations. In this talk, I will focus on collective magnetic excitations (i.e. magnons). I will briefly discuss how these excitations can be coupled to charge degrees of freedom - a key concept underlying spintronics - highlighting recent progress involving processes at terahertz frequencies [1-2]. The main part of the talk will address the optical manipulation of magnons. I will show how resonant excitation of specific magnetic and electronic transitions drives the system into non-equilibrium states in which magnon modes, that are not directly excited, become activated and substantially modified. In particular magnon frequencies can be modified up to 40% of their original value at room temperature in a 20 nm thick magnet [3]. Alternatively, the resonant pumping of high-momentum magnons can be explored by means of mid-infrared laser pulses. This excitation pathway activates distinct zone-center modes whose amplitudes and frequencies are strongly renormalized compared to their equilibrium values [4]. I will conclude by outlining future perspectives of this research direction, with the long-term goal of achieving arbitrary optical control over magnon dispersion relations in quantum materials.
References:
[1] T. Mezger et al. Physical Review Letter 135, 076702 (2025)
[2] M. Cimander et al. Nature Communications 17, 1480 (2026)
[3] V. Wiechert et al. Nature Communications 17, 145 (2026)
[4] C. Schoenfeld et al. Science Advances 11, 25 (2025)
Bio：Dr. Davide Bossini received his PhD at the Radboud University Nijmegen (The Netherlands) in 2015, focusing on the optical generation of coherent magnons in dielectric materials with several technique. He spent then two years as a postdoctoral fellow in the University of Tokyo, supported by a JSPS (Japanese Society for the Promotion of Science) fellowship. He was then appointed as junior group leader at the TU Dortmund (Germany). After being awarded the prestigious Emmy Noether grant from the German Science Foundation (DFG), he moved to the University of Konstanz (Germany), where he set up his own junior group. Dr. Bossini’s contribution to the field of optical control of quantum materials has been recognised by the IEEE Magnetics Society “Early Career Award” (2019) and the I-LAMP “Early Career Award” (2020).
