Berlin 2024 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 21: Focus Session: Spins on Surfaces studied by Atomic Scale Spectroscopies III
O 21.7: Vortrag
Dienstag, 19. März 2024, 12:15–12:30, MA 004
Syncing of stochastically switching atomic orbital memory — •Kira Junghans1, Hermann Osterhage1, Werner M. J. van Weerdenburg1, Ruben Christianen1, Eduardo J. Domínguez Vázquez2, Hilbert J. Kappen2, and Alexander A. Khajetoorians1 — 1Institute for Molecules and Materials, Radboud University Nijmegen, the Netherlands — 2Donders Institute for Neuroscience, Radboud University Nijmegen, the Netherlands
Stochastically fluctuating multi-well systems are a promising route toward designing neuromorphic hardware. One challenge is finding tunable material platforms that exhibit such multi-well behavior.
The recently discovered atomic Boltzmann machine provides such a platform, where orbital memory states represent binary stochastic units [1,2]. Here, we investigate the response of orbital memory states of Fe and Co atoms on black phosphorus [2,3] to a sinusoidal input voltage using scanning tunneling microscopy. For both species, we observe synchronization of the state occupation to the sinusoidal signal. The state favorability of Fe atoms also shows a frequency-dependent response to the drive, which can be tuned by the input parameters. In contrast to Fe, there is no significant frequency-dependence in the state favorability for Co atoms. The response of the state favorability can be traced to the difference in the voltage-dependent switching rates of the two species based on the Poisson process model.
[1] B. Kiraly et al., Nat. Nanotechnol. 16, 414 (2021).
[2] B. Kiraly et al., Nat. Commun. 9, 3904 (2018).
[3] B. Kiraly et al., Phys. Rev. Research 4, 33047 (2022).
Keywords: Orbital memory; Boltzmann machine; synchronization; STM