Regensburg 2022 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 25: Ultrafast Magnetization Effects 2
MA 25.1: Vortrag
Mittwoch, 7. September 2022, 15:00–15:15, H43
Light-induced magnetization dynamics in a ferromagnetic semiconductor — •Jingwen Li1, Masakazu Matsubara2, Kristin Kliemt3, Nazia Kaya3, Isabel Reiser3, Cornelius Krellner3, Johann Kroha4, Shovon Pal5, and Manfred Fiebig1 — 1ETH Zurich, Switzerland — 2Tohoku University, Japan — 3Goethe University Frankfurt, Germany — 4Bonn University, Germany — 5NISER Bhubaneshwar, India
Ferromagnetic semiconductors are a rare class of materials that can provide a new platform with spin degrees of freedom in electronic and optical devices. All-optical control of the magnetic order is a demanding task, however. As one prototype example, EuO is intriguing for its high Curie Temperature (Tc = 69 K) induced by the indirect exchange interactions between the Eu atoms. The interactions can be enhanced by photo-doping in an ultrafast non-thermal way, strengthing the ferromagnetic order. This was verified in the ferromagnetic phase of the material [1], but evidence for an enhancement of the magnetic order around or above Tc is still lacking. In this contribution, we show the photo-induced presence of magnetic ordering even at temperatures higher than Tc by making use of the temperature-dependent spectral shift accompanying the magnetically ordered states using optical pump-probe spectroscopy. In optical reflection experiments, we observe two distinct types of ultrafast processes related to the optically driven magnetic order that show different relaxation rates. Our results provide clear evidence of short-range magnetic order above Tc, originating from the so-called exciton magnetic polarons.