Research students at Queen’s University Belfast have used modified experimental geometry originally dating back to 1911, to measure for the first time the exact electronic properties of a ‘domain wall’ – two-dimensional scaled sheets. nanoscale embedded in a crystalline material – which may be more electrically conductive than the surrounding crystal itself. Useful as nanoscale electrical connections, they can also be created, destroyed and moved – promising new, fully reconfigurable devices with the ability to completely change function or self-repair in the event of failure.

Conor McCluskey, one of the students who led the experiment at Queen’s School of Mathematics and Physics, said: “We now know that the electrons that carry the electric current inside these domain walls move exceptionally fast at room temperature. They move at speeds similar to electrons in graphene – which is a wondrous material hailed for its conductive properties and its discovery won a Nobel Prize in 2004.

“Usually when an electron carries a current, it ends up scattering over the atoms of the material. This blocks the electron in its journey and creates electrical resistance. We have found that the charges in these domain walls can move for a very long time before being dispersed – on average they move quite quickly This property itself is very useful for high speed electronics, but combined with the fact that domain walls themselves are fully mobile and reconfigurable could be a game-changer for nanotechnology.

Conor added that while electronic components have become smaller and smaller, the point has been reached where further reduction in size will affect component reliability. “The next generation of devices will need to rely on materials that do something different and movable domain walls could give us just that. Our discovery sheds light on what exactly is going on in these domain walls to make them behave the way they do, and this understanding is key to creating true domain wall devices that work reliably.

Professor Marty Gregg, Queen’s School of Mathematics and Physics, comments: “There is a great analogy to Professor Nava Setter, a pioneer in domain wall research, in describing the potential applications of domain walls in nanoelectronics. You can imagine an electrical circuit like a city, a complex arrangement of buildings, all interconnected by roads.

“Similarly, a circuit comprises electronic components linked together by electronic connections. If those power connections were instead provided by moveable, reconfigurable domain walls, it would be like having the ability to change the layout of city roads in an instant, allowing you a direct path to your destination. Now we are beginning to reveal the true electronic properties of the domain walls themselves. Rather than just acting as connections, it seems they can act as functional components themselves. By sticking to the analogy, we can move and recreate the actual buildings in the city, rather than just the connections between them. »

He adds: “With circuits capable of reconfiguring or repairing themselves, we could have tiny electronic devices that are extremely flexible and adaptable. It could make a huge difference to society. For example, the ability to repair electronic devices that are not easily accessible, such as in medical implants, or satellites in orbit, would be a huge advantage.

The Queen’s University team worked in collaboration with teams from France (Dr Manuel Bibes), the United States (Professor Alexei Gruverman) and the Republic of Ireland (Professor Ursel Bangert). The results have been published in Advanced Materials

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