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.