Experimental evidence of inertial dynamics in ferromagnets

Kumar Neeraj; Nilesh Awari; Sergey Kovalev; Debanjan Polley; Nanna Zhou Hagström; Sri Sai Phani Kanth Arekapudi; Anna Semisalova; Kilian Lenz; Bertram Green; Jan-Christoph Deinert; Igor Ilyakov; Min Chen; Mohammed Bowatna; Valentino Scalera; Massimiliano d'Aquino; Claudio Serpico; Olav Hellwig; Jean-Eric Wegrowe; Michael Gensch; Stefano Bonetti

arXiv · 1910.11284

Experimental evidence of inertial dynamics in ferromagnets

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Abstract

The understanding of how spins move at pico- and femtosecond time scales is the goal of much of modern research in condensed matter physics, with implications for ultrafast and more energy-efficient data storage. However, the limited comprehension of the physics behind this phenomenon has hampered the possibility of realising a commercial technology based on it. Recently, it has been suggested that inertial effects should be considered in the full description of the spin dynamics at these ultrafast time scales, but a clear observation of such effects in ferromagnets is still lacking. Here, we report the first direct experimental evidence of inertial spin dynamics in ferromagnetic thin films in the form of a nutation of the magnetisation at a frequency of approximately 0.6 THz. This allows us to evince that the angular momentum relaxation time in ferromagnets is on the order of 10 ps.

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Kumar Neeraj, Nilesh Awari, Sergey Kovalev, Debanjan Polley, Nanna Zhou Hagström, Sri Sai Phani Kanth Arekapudi, Anna Semisalova, Kilian Lenz, Bertram Green, Jan-Christoph Deinert, Igor Ilyakov, Min Chen, Mohammed Bowatna, Valentino Scalera, Massimiliano d'Aquino, Claudio Serpico, Olav Hellwig, Jean-Eric Wegrowe, Michael Gensch, Stefano Bonetti. 2019-10-24. Experimental evidence of inertial dynamics in ferromagnets. https://arxiv.org/abs/1910.11284

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