‘Molecular traffic light’ developed at UL helps solve 50-year-old physics puzzle

24 Mar 2020

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Researchers at UL have helped discover a molecule that could have a major impact on how data is stored and processed.

An international research team, including researchers from the University of Limerick’s (UL) Bernal Institute, has discovered a simple metal-organic molecule that goes beyond simple on-off binary computing logic. Instead, it can switch between three distinct, long-lived states.

This is the first demonstration of a so-called ternary ‘molecular traffic light’ device and could have major implications for data storage and processing. This device could offer low-energy means of storing and processing unrestructured big data gathered using the internet of things and AI.

Damien Thompson, an associate professor in physics at UL, is leading a team that used simulations generated by the Irish Centre for High-End Computing supercomputer. These simulations showed that the surprisingly stable third state is made possible by an unequal sharing of electrons between different sides of the molecule.

In doing so, it helps solve a 50-year-old physics mystery.

“Here, we managed to push way beyond industry roadmaps by finding a ternary resistive memory device with three states that are well-separated from each other in terms of conductance and, just as importantly, stay working away perfectly for weeks on end,” Thompson said.

“The trick to this first commercially viable multi-level computing device is a slightly arcane physical phenomenon called ‘charge disproportionation’ or symmetry breaking, which we proved using computer simulations.”

No longer a curiosity

He added that scientists have long noticed that certain materials can ‘breathe’ in an electric or magnetic field. Furthermore, in some cases, the electron cloud around the molecules can lose its symmetry.

“This has remained an academic curiosity, until now, lacking technological relevance because it has always been associated with a big change in temperature or pressure,” Thompson said.

“Whereas here, the third asymmetric state is created simply by allowing current to flow through the device and it persists over a broad temperature range, so it is suitable for most conventional computing as well as future applications emerging from the symbiosis between physics, computing and biology.”

A study on the findings of the research has been published to Nature Nanotechnology.

Colm Gorey was a senior journalist with Silicon Republic