ATRONICS explored how the behavior of key electronic components can be emulated based on individual improper ferroelectric domain walls and to what extend such functional units can be interconnected to realize more complex devices and networks, such as logic gates and combinatorial logic circuits.
A first important step was to learn how to nanostructure our materials and achieve device-relevant geometries without altering the electronic responses of the ferroelectric domain walls. The latter is highly non-trivial as energetic charged atoms are used for nanostructuring. As a consequence, this method can completely change the electronic structure, requiring careful control of the ablation process. In addition, whenever the size of a physical system is reduced, confinement effects come into play so that nano-sized systems do not necessarily exhibit the same properties as their macroscopic counterparts. Thus, it was a real breakthrough for us when we managed to reduce the thickness of our materials down to 10 – 100 nm without losing the functionality of the domain walls we are interested in. For example, we observed that the domain walls in our thin samples exhibit high and low resistance states between which we can switch by controlling the applied voltage, mimicking the behavior of a digital switch. To understand the atomic-scale physics of the walls, we combined different state-of-the-art microscopy techniques and also develop new experimental methodologies.
In order to progress towards the different envisioned device applications, we also established procedures to mount our nanostructured samples on biasing chips or electrically contact them in other ways. The latter was a crucial precondition to produce the two- and three-terminal device architectures we used in our proof-of-concept experiments. In addition, we successfully demonstrated a substantial impact of environmental conditions on the electronic conduction of the domain walls (e.g. gas atmosphere and temperature). Importantly, the domain wall responses are more pronounced than in the surrounding domains. For example, we managed to sense changes in oxygen partial pressure, which are detectable as a reversible change in the local conductivity, opening the door towards domain-wall-based environmental sensors.
The research activities of ATRONICS showed the possibility to achieve ultra-small electronic components and sensors based on individual domain walls and introduced novel concepts promoting the transition from nano- to atomic-scale electronics.
The scientific results led to more than 40 publications in peer-reviewed journals, including several high-impact papers. The ATRONICS team actively disseminated these results at international conferences and workshops through plenary lectures, invited and contributed talks, and poster presentations. In addition, we engaged with the broader public by sharing key breakthroughs through news features and outreach articles, helping to raise awareness of the project’s scientific impact.
