Chiral spin textures are the smallest magnetic entities, offering topological stability and tunability, making them ideal for energy-efficient computing1,7. Their equilibrium properties arise from the interplay between collinear exchange and chiral Dzyaloshinskii-Moriya interactions (DMI), stabilizing structures like skyrmions. In contrast, their dynamic behavior is governed by non-equilibrium phenomena such as chiral damping. In the first part of my talk, I will present our studies on equilibrium magnetization in a tunable chiral multilayer platform1. Using optical and X-ray spectroscopy, we observed that the Heisenberg exchange constant (A)3 and DMI strength (D) can vary inversely—challenging conventional theories. Element-specific insights highlight the key role of orbital magnetism in tuning chirality2. Next, I will address non-equilibrium phenomena, focusing on chiral damping (CD). Our first time observation of chiral damping using BLS technique, allows exploration of this quantity regardless of magnetic anistropy, earlier limited to PMA systems4. The origin of this effects needs to be understood, our measurmenst reveal interesting correlations with chiral energy and magnetic textures5.These findings deepen our understanding of non-equilibrium chiral spin dynamics. Armed with the tunability of equillibrium spin texture characteristics, we explored the microwave resonance behavior of chiral multilayers. Broadband microwave and Lorentz microscopy measurements revealed a distinct hysteretic resonance from dense Néel spin textures, which can be reconfigured linearly or non-linearly via skyrmion nucleation under tailored magnetic fields. This tunability enables reproducible magnon responses well-suited for reservoir computing6. Our integration of skyrmions into tunnel junctions further establishes their potential as energy-efficient, all-electrical computing bits7.
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​ References :
​ 1. Soumyanarayanan, A, et al. “Tunable room-temperature magnetic skyrmions in Ir/Fe/Co/Pt multilayers.” Nature materials 16, (2017): 898-904.
​ 2. T.S. Suraj, et al., “Orbital anisotropy evolution with symmetric and asymmetric exchange” (in Prep.)
​ 3. Böttcher, T., T. S. Suraj, et al. “Quantifying symmetric exchange in ultrathin ferromagnetic films with chirality”. Physical Review B, (2023), 107(9), 094405.
​ 4. Dae-Yun Kim, …, T. S. Suraj, et al., “Chiral damping of magnons”. Physical Review Letters, (2024), 133(15), p.156704.
​ 5. T S. Suraj et al. “Anatomy of chiral damping” (in Prep.)
​ 6. T.S. Suraj, et al., “Dynamically programmable GHz resonances of chiral spin texture ensembles” Submitted (2024).
​ 7. S. Chen, .., T. S. Suraj, et al.“All-electrical skyrmionic magnetic tunnel junction”. Nature (2024) 627, 522.
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More information :https://www.spintec.fr/seminar-spectroscopic-signatures-of-chirality-and-resonances-for-designer-magnonics/​

Videoconference ​: https://univ-grenoble-alpes-fr.zoom.us/j/98769867024?pwd=dXNnT3RMeThjYStybGVQSUN0TVdJdz09