PhD Candidate for Ultra-low Temperature Scanning Tunnelling Microscopy/Spectroscopy of Individual...

With leading research into fundamental physics, we can answer important questions about the world of today and tomorrow. This requires curious individuals who want to push the experimental boundaries of science with their talent and expertise. As a PhD Candidate at the Scanning Probe Microscopy department, you get to explore the future of brain-inspired computing with our state-of-the-art facilities.

The goal of this PhD project is to explore bottom-up atomic spin systems to understand multi-well energy landscapes and their use for brain-inspired computing.

One of the paradigms in brain-inspired computing is based on creating attractor networks, where metastable local minima are used to represent information. In physics, such multi-well landscapes can be created from glassy spin systems, which exhibit metastable order. In 2020 (1), we hypothesised that atomic arrays of spins can be used to create such multi-well landscapes by using long-range interactions that lead to frustration. In 2020, we made the first observation of a magnetic system that exhibits a related so-called self-induced spin glass state, in elemental Nd (2). At the same time, we found that atomic systems can also exhibit multi-well behaviour (3). Using the concept of orbital memory as we experimentally observed in 2018 (4), we showed that arrays of Co atoms can be used to create a Boltzmann machine, in which the stochastic dynamics of arrays of Co atoms can be used to present neurons and synapses in this model. We have continued to study the physical origins of orbital memory, and its manifestation in other atomic systems (5-6).

Relevant references:
(1) A. Kolmus, M. I. Katsnelson, A. A. Khajetoorians, H. J. Kappen, Atom-by-atom construction of attractors in a tunable finite size spin array. New Journal of Physics 22, 023038 (2020).
(2) U. Kamber et al., Self-induced spin glass state in elemental and crystalline neodymium. Science 368, eaay6757 (2020).
(3) B. Kiraly, E. J. Knol, W. M. J. van Weerdenburg, H. J. Kappen, A. A. Khajetoorians, An atomic Boltzmann machine capable of self-adaption. Nature Nanotechnology 16, 414-420 (2021).
(4) B. Kiraly et al., An orbitally derived single-atom magnetic memory. Nature Communications 9, 3904 (2018).
(5) B. Kiraly, E. J. Knol, A. N. Rudenko, M. I. Katsnelson, A. A. Khajetoorians, Orbital memory from individual Fe atoms on black phosphorus. Physical Review Research 4, 033047 (2022).
(6) E. J. Knol et al., Gating Orbital Memory with an Atomic Donor. Physical Review Letters 128, 106801 (2022).

We have in total 2 positions available.