中心系列报告29 — Bernhard Keimer

报告题目：Strain modulation of magnons and paramagnons

摘要：

We will present Raman Scattering and Resonant Inelastic X-ray Scattering (RIXS) data on the magnetic ground state as well as antiferromagnetic magnon and paramagnon excitations in 4d- and 5d-electron compounds under uniaxial strain. In spin-orbit Mott insulators including Ca₂RuO₄ and Sr₂IrO₄, we have discovered strain-induced magnetic phase transitions and strain-modulated magnon anomalies, which offer perspectives for THz magnonics. [1,2] In metallic Sr₂RuO₄, we have observed a large strain-induced softening of paramagnons, with possible implications for unconventional superconductivity. [3,4] Related data on metallic (but nor superconducting) Sr₂RhO₄ will also be presented. [5,6]

[1] Hun-Ho Kim, Kentaro Ueda, Suguru Nakata, Peter Wochner, Andrew Mackenzie, Clifford Hicks, Giniyat Khaliullin, Huimei Liu, Bernhard Keimer, Matteo Minola, Nature Communications 13, 6674 (2022). 

[2] Lichen Wang, Huimei Liu et al., to be published. 

[3] H. Suzuki, L. Wang, J. Bertinshaw, H. U. R. Strand, S. Käser, M. Krautloher, Z. Yang, N. Wentzell, O. Parcollet, F. Jerzembeck, N. Kikugawa, A. P. Mackenzie, A. Georges, P. Hansmann, H. Gretarsson, B. Keimer, Nature Communications,14 7042 (2023). 

[4] Lichen Wang et al., to be published. 

[5] Lichen Wang et al., Phys. Rev. Lett. 132, 116502 (2024). 

[6] Valentin Zimmermann et al., npj Quantum Materials 8, 53 (2023).

简 历：

Bernhard Keimer grew up in Germany and studied physics at the Technical University of Munich (1983-1986) before transferring to the Massachusetts Institute of Technology, where he received his PhD in 1992. After a year as postdoctoral associate at MIT, he became Assistant Professor at Princeton University in 1992, where he was promoted to Associate (1996) and Full (1997) Professor. In 1998, he became Director at the Max Planck Institute for Solid State Research, a position he has held until today. He was appointed Honorary Professor at the University of Stuttgart in 2000, and Adjunct Professor at the University of British Columbia in 2020. His service to academic self-administration includes chairmanship of the Scientific Council of the Max Planck Society (2020-2023) and of the University Council of the University of Stuttgart (2015-today).  He has served on numerous advisory and review panels and editorial boards (including Physical Review Letters 2003-2005, and Science 2000-2012), and he chaired the Gordon Research Conference on Superconductivity (2013) and the Conference on Spectroscopies in Novel Superconductors (2016). His scientific awards include the Gottfried Wilhelm Leibniz Prize (2011) and the Heike Kamerlingh Onnes Prize (2022).