报告题目：Femtosecond coherent manipulation of magnetism in solids

报告人：Davide Bossini

时间：2023-11-22 10：00

地点：物理系理科楼C302

摘要：The wildly growing field of light-matter interaction in solids is currently addressing several fundamental questions. A major topic of investigation concerns the possibility to optically manipulate the macroscopic electronic, magnetic and lattice properties of condensed matter. The development of novel pulsed-laser sources has enabled scientists to address the following scientific question: Can the electric field of laser pulses change the physical interactions defining the Hamiltonian of a solid on fundamental timescale? In my talk I will outline the different pathways to induce collective coherent spin excited states in magnetic materials via light pulses. After a brief summary of the literature, I will then discuss our recent approach to the aforementioned fundamental question, which relies on the resonant drive of pairs of high-energy magnons in the weak ferromagnet α-Fe2O3, with wavevector near the edges of the Brillouin zone. This unprecedented concept results in strongly perturbing the entire magnetic system of the material, in particular: i) spin wave modes with different wavevectors are excited and amplified; ii) coupling between magnon modes is observed and, most importantly, iii) the eigenfrequencies of magnons are modified, which demonstrates a modification of the magnetic Hamiltonian. All these groundbreaking observations are rationalised in view of a resonant impulsive stimulated Raman scattering mechanism. We also derived a quantum mechanical model of the modification of the magnon spectrum due to the laser-induced magnon population. Our results set the first milestone towards an arbitrary optical tailoring of the Hamiltonian of solids.

报告人简介：Prof. Davide Bossini got his PhD in Nijmegen (The Netherlands) from the group of Prof. Theo Rasing and Prof. Alexey Kimel in 2015. He moved to Tokyo to work as a postdoc in the group of Prof. Kuwata-Gonokami, supported by a fellowship of the Japanese Society for the Promotion of Science (JSPS). In 2017 he moved to Germany (TU Dortmund), where he took a position of senior postdoc. Shortly after, he was awarded the Emmy Noether grant from the German science foundation (DFG), allowing him to establish his independent junior group in a German academic institution. He moved to Konstanz where he is developing his research group. In 2017 he received a postdoc Award from the journal Applied Sciences. In 2019 he was awarded the early-career Award from the IEEE Magnetics Society. In 2020 he received also the iLAMP early-career Award.