SKM 2023 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 20: Poster: Spins and Magnetism at Surfaces

O 20.2: Poster

Montag, 27. März 2023, 18:00–20:00, P2/EG

Tuning the frequency response of stochastically switching orbital states of Fe and Co atoms on black phosphorus — •Kira Junghans, Hermann Osterhage, Werner M. J. van Weerdenburg, Niels P. E. van Mullekom, Ruben Christianen, Eduardo J. Domínguez Vázquez, Hilbert J. Kappen, and Alexander A. Khajetoorians — Radboud University, Nijmegen, The Netherlands

The concept of the atomic Boltzmann machine (BM) is based on the recently discovered idea of orbital memory [1,2]. Orbital memory is characterised by two stable valency configurations [2,3]. By applying a bias voltage to a scanning tunneling microscopy (STM) tip above a threshold, stochastic switching between the states can be induced. The favorability of the individual states depends strongly on the applied bias voltage.
Unlike coupled spins under exchange, leading to bistability, coupled atoms that exhibit orbital memory show multi-stability in their stochastic dynamics. This multi-well energy landscape serves as a basis for the BM and realizing multiple time scales.
Here, we show that single Fe and Co atoms respond frequency and amplitude dependent to an AC component of the applied bias. In addition, we present how the stochastic behavior of coupled atoms in the multi-well regime respond to a harmonic drive voltage.

[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).