Tel Aviv University

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https://meeting.tencent.com/dm/aYrHhqQrCcYU

腾讯会议：107-749-237

报告摘要：

The Einstein-de Haas effect conventionally describes the coupling of magnetization and mechanical rotation due to angular momentum conservation. On ultrashort timescales, such as during the sudden demagnetization of a material following the excitation with a laser pulse, the ultrafast Einstein-de Haas effect describes the coupling of spin and orbital angular momentum to the angular momentum of circularly polarized (chiral) phonons and strain waves. Here, we showcase the inverse mechanism: chiral phonon modes, driven by an ultrashort terahertz pulse, can induce a magnetization in both nonmagnetic and magnetic materials. We use a combination of phenomenological modeling and density functional theory calculations to simulate the coherent excitation of chiral phonons, which generate real and effective magnetic fields within the material, which subsequently produces a magnetization. We show that magnetizations of up to several Bohr magneton can possibly be induced. This mechanism can be seen as a phonon Barnett effect, the inverse of the Einstein-de Haas effect. At the same time, it can be considered a phonon analog of the inverse Faraday effect, in which circularly polarized (chiral) light induces a magnetization in materials. Phonon inverse Faraday/Barnett effects provide a new avenue to control the magnetic order of materials on ultrafast timescales.

报告人简介：

Dr. Dominik Juraschek obtained his PhD from the Department of Materials at ETH Zurich in 2018 and was awarded the Early Postdoc Mobility Fellowship of the Swiss National Science Foundation. He continued his postdoctoral research at the School of Engineering and Applied Sciences at Harvard University from 2019 to 2021. He joined School of Physics and Astronomy of Tel Aviv University in October 2021 as an Assistant Professor, where he leads the Dynamical Quantum Matter group. As a theoretical and computational physicist, Dominik has done pioneering work in the field of nonlinear phononics and ultrafast dynamics in quantum materials, involving predictions of the phonon Zeeman and phonon inverse Faraday effects.

邀请人：王亚娴 副研究员

联系人：张坚地 研究员