STROBE Seminar: Dr. Davide Bossini, “Femtosecond electric-field induced manipulation of coherent magnetic excitation”
Abstract: The wildly growing field of antiferromagnetic spintronics is currently addressing several fundamental questions. A major topic of investigation concerns the generation and manipulation of coherent magnons on the ultrafast timescale. The development of novel pulsed-laser sources has enabled scientists to address the following scientific question: which magnetic excited state can be induced by resonantly driving coherent magnons throughout the Brillouin zone? In my talk, I will outline our approach to this open issue, which relies on the resonant drive of pairs of high-energy magnons in the weak ferromagnet α-Fe2O3 (hematite), with wavevector near the edges of the Brillouin zone. This unprecedented concept results in a strong perturbation of the entire magnetic system of the material, in particular: i) magnon modes with different wavevectors are excited and amplified; ii) the eigenfrequencies of magnons are modified, which demonstrates a modification of the magnon dispersion; iii) a coupling between magnon modes that are orthogonal eigenstates of the magnetic Hamiltonian of the material is observed. Additionally, the effect of light on the magnetic system is quantified by quantitatively estimating the modification of the magnetic interactions. All these observations are rationalised in view of a resonant impulsive stimulated Raman scattering mechanism. Our results offer perspectives to establish an all-optical arbitrary tailoring of the spectrum of the magnetic excitations of a given material on the fundamental timescales.
Speaker Bio: Dr. Bossini is a junior research group leader (Emmy Noether program) in experimental solid state Physics at the University of Konstanz, Germany. He is mostly interested in controlling the magnetic and electronic properties of solid state compounds, on the ultrafast time-scale. He is PI of 3 national projects and awardee of the Emmy Noether grant, and author of more than 20 papers in international journals. He got his PhD from Radboud University in the Netherlands in 2015. He then joined The University of Tokyo in Japan, first as a Project Researcher and then as a JSPS (Japanese Society for the Promotion of Science) Postdoctoral Fellow. In 2020, He became a non-tenured assistant Professor at Fakultät Physik Der TU-Dortmund, Germany, where he worked in a research team which aims at controlling magnetism in condensed matte with light. He received several awards, including IEEE Magnetics Society Early Career Award in 2019, “For contributions to the femtosecond coherent manipulation of high-energy short-wavelength magnons in antiferromagnets and for the ultrafast activation of magnetoelectricity.”
Dr. Davide Bossini