Disentangling the Ultra-fast Demagnetization and Spin Accumulation in Magneto-optical Detection

Title: Disentangling the ultra-fast demagnetization and spin accumulation in magneto-optical detection
When: Friday, March 21, 2025, 13:00
Place: Department of Theoretical Condensed Matter Physics, Faculty of Sciences, Module 5, Seminar Room (5th Floor)
Speaker: Alberto Anadón / Université de Lorraine, CNRS, Nancy, France

Efficient generation and detection of ultrafast electrical signals can lead to significant advancements in material science, data processing and communication technology. In this sense, THz spin currents from magnetic materials provide a promising framework to overcome some of the challenges of current THz technology, primarily due to their large bandwidth and tunability [1]. Therefore, accurately quantifying and understanding such ultrafast spin currents is a major challenge in the field of ultrafast magnetism. For this reason, the spintronics community has invested vastly into studying both the process of ultrafast demagnetization [2] and the transport of spin currents into other layers either by THz spectroscopy [1], analysis of ultrafast spin torques [3] or even direct optical detection of the resulting spin accumulation [4–6]. In this work, we carefully analyze magneto-optical signals in a series of ferromagnetic samples, in order to deconvolute the signals resulting from the changes in local magnetization and angular momentum transport across layers. During this talk, we will show different signatures of the magneto-optical signals, we will compare rotation and ellipticity, and will present a simple model that describes the detected signals. These observations could shed some light into the longstanding controversy on the differences observed in the rotation and ellipticity in the magneto-optical signals at ultra-short time scales [7–10].

References:

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