Dresden 2026 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 15: Spins on surfaces at the atomic scale I

O 15.3: Vortrag

Montag, 9. März 2026, 15:45–16:00, WILL/A317

Creating multi-well energy landscapes from coupled orbital memory states — •Kira Junghans, Niek M. M. Aarts, Hermann Osterhage, Julián D. Rojas-Castillo, and Alexander A. Khajetoorians — Institute for Molecules and Materials, Radboud University, Nijmegen, The Netherlands

The interaction between atomic spins on surfaces is usually dictated by the exchange interaction. Its short-range nature strongly favors spin orientations that are either ferro- or antiferromagnetic. Recently, it was shown that memory can be created from an atomic spin using its valency [1]. Unlike the exchange interaction, it was shown that the interactions between orbital memory elements are long-range. This can lead to complex stochastic dynamics often needed in computational schemes based on theoretical neuroscience [2]. Exploiting this new functionality requires a deeper understanding of the nature of the interaction as well as the uniqueness of this material system.

Here, we study the stochastic dynamics of Co and Fe atoms on black phosphorus with scanning tunneling microscopy and spectroscopy. We quantify how the state favorability and lifetimes are influenced in dimers at different distances and by the neighboring atoms' state. We find that heterogenous dimers can also lead to complex stochastic noise, analogous to multi-well behavior. Furthermore, we investigate the dynamics of multiple coupled atoms and show that the state favorabilities can be tuned by the states of all surrounding atoms.

[1] B. Kiraly et al., Nat. Comm. 9, 3904 (2018).

[2] B. Kiraly et al., Nat. Nanotechn. 16, 414 (2021).

Keywords: orbital memory; scanning tunneling microscopy (STM); atomic Boltzmann machine