Regensburg 2019 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 29: Quantum information systems
MA 29.2: Vortrag
Mittwoch, 3. April 2019, 09:45–10:00, H53
Spin dynamics of Ho single atom magnets — F. Donati1, 2, S. Rusponi2, L. Persichetti3, S. Stepanow3, •A. Singha1, 2, R. Baltic2, C. Wäckerlin2, M. Pivetta1, C. Nistor3, J. Dreiser4, K. Kummer5, E. V.-Fort5, D. Juraschek3, N. Spaldin3, H. Brune2, and P. Gambardella3 — 1IBS Center for Quantum Nanoscience, South Korea — 2EPFL, Switzerland — 3ETH Zurich, Switzerland — 4PSI, Switzerland — 5ESRF, France
Single atom magnets represent the smallest unit of matter that can be used to store and manipulate information. The strongly localized 4f electrons in rare earth atoms allow only weak interaction with the environment, leading to long magnetic lifetimes as recently discovered for single Ho atoms adsorbed on MgO/Ag(100) [Science 352, 318 (2016)]. Reading and writing their magnetic states at the atomic scale further demonstrated the potential of these atoms as magnetic bits up to 45 K [PRL 121, 027201 (2018)]. Here we investigate the spin reversal mechanism of the Ho atoms by exploring the effects of temperature and external magnetic field on the magnetic lifetime using x-ray magnetic circular dichroism. At 0.01 T, the lifetime of Ho atoms is 1500 s up to 10 K and decreases with temperature following an exponential Arrhenius law with an effective barrier of 4 ± 0.5 meV. However, spin reversal is suppressed in a strong magnetic field of 6.8 T, and the magnetic lifetime remains constant at about 1200 s up to 30 K. Our results suggest that the Ho atoms can mainly exchange energy and angular momentum with the surface via localized vibrational modes of quantized energy, which limits the effectiveness of spin reversal mechanisms.