SKM 2023 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 33: Spins on Surfaces at the Atomic Scale III

O 33.9: Vortrag

Dienstag, 28. März 2023, 12:45–13:00, REC C 213

Stochastic dynamics of individual and coupled orbital memory on black phosphorus — •Hermann Osterhage, Werner M. J. van Weerdenburg, Niels P. E. van Mullekom, Ruben Christianen, Kira Junghans, Eduardo J. Domínguez Vázquez, Hilbert J. Kappen, and Alexander A. Khajetoorians — Radboud University, Nijmegen, The Netherlands

Recently, the dynamics of Co atoms adsorbed on a black phosphorus (BP) surface were shown to emulate a Boltzmann machine (BM) [1]. The BM relies on a tunable multi-well energy landscape, realized in the stochastic switching of coupled atoms which exhibit orbital memory [2]. Stochastic switching between orbital memory states can be induced using scanning tunneling microscopy (STM). The system response depends on interatomic distances and is adaptable to the position of the STM tip and to the applied DC bias [2].

Here, we present the response of individual and coupled Fe and Co atoms on BP to AC input voltages (i.e. frequency and amplitude response), measured using STM down to millikelvin temperatures. We find a frequency response of the orbital memory of single atoms. The changes in orbital state population with varying AC frequency can be derived from the switching dynamics in the DC case. The interatomic coupling is discussed based on changes in switching rates conditioned on the state of a second atom. Also the AC stochastic response in the multi-well limit will be discussed.

[1] B. Kiraly et al., Nat. Nanotechnol. 16, 414 (2021).
[2] B. Kiraly et al., Nat. Commun. 9, 3904 (2018).