Berlin 2024 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 28: Thin Films: Magnetic Anisotropy
MA 28.2: Vortrag
Mittwoch, 20. März 2024, 15:15–15:30, EB 107
Tuning perpendicular magnetic anisotropy via hydrogen concentration — Madeleine Bischoff1, Olav Hellwig2,3, Karin Leistner1, and •Markus Gößler1 — 1Institute of Chemistry, Chemnitz University of Technology — 2Institute of Physics, Chemnitz University of Technology — 3HZDR Dresden-Rossendorf
A strong perpendicular anisotropy is crucial for modern magnetic data storage devices, providing two stable magnetization directions on a bit scale. Post deposition control of this anisotropy via voltage, promises a drastic improvement of the energy-efficiency for the writing process in such devices. Here, we investigate electrochemical hydrogen-loading in aqueous electrolytes as a voltage-controlled magneto-ionic method[1] for the modulation of anisotropy in perpendicularly magnetized Co/Pd multilayers. Using both in situ electrochemical Kerr microscopy and flow-cell coulometry, we can measure coercivity directly as a function of hydrogen concentration. We find a continuous increase of coercivity up to 20% at a concentration smaller than 0.3 hydrogen atoms per metal atom, which we attribute to hydrogen-induced changes in the anisotropy. Our findings agree with recent DFT predictions of hydrogen in Co/Pd[2]. We argue that the degree of intermixing between Co and Pd atoms during sputter deposition determines the maximum attainable hydrogen concentration in our films and therefore the maximum anisotropy change. Our work highlights the importance of the concentration in ionic devices, which has previously been neglected in the magneto-ionic literature. [1] M. Gößler et al., Small 15, 1904523 (2019) [2] K. Klyukin et al., Phys. Rev. Mater. 4, 104416 (2020)
Keywords: Magneto-Ionic; PMA; magnetic multilayers; hydrogen