A team of researchers have manufactured the world’s smallest technology – just two atoms thick – potentially creating new methods of storing information.
The novel discovery, accomplished by researchers at Tel Aviv University, is not only the world’s smallest technology ever unearthed but demonstrates to be one of the most durable and stable materials in nature, permitting quantum-mechanical electron tunnelling that can possibly enhance the information processing capabilities of future technologies.
Dr Ben Shalom, from the Raymond and Beverly Sackler School of Physics and Astronomy, said: “Our research stems from a curiosity about the behaviour of atoms and electrons in solid materials, which has generated many of the technologies supporting our modern way of life. We (and many other scientists) try to understand, predict, and even control the fascinating properties of these particles as they condense into an ordered structure that we call a crystal.
“At the heart of the computer, for example, lies a tiny crystalline device designed to switch between two states indicating different responses – ‘yes’ or ‘no’, ‘up’ or ‘down’ etc. Without this dichotomy – it is not possible to encode and process information. The practical challenge is to find a mechanism that would enable switching in a small, fast, and inexpensive device.”
Endless possibilities for the world’s smallest technology
Conventional computer technology contains minuscule crystals that are comprised of around one million atoms – around 100 atoms in height, width, and thickness – meaning that millions of these devices can be situated in the area the size of a coin, each switching at around one million times per second.
Now, the researchers have significantly evolved this technology by minimising the thickness of the crystalline devices to a mere two atoms, making it the world’s smallest technology to date. The thin structure is proficient in allowing memories based on the quantum abilities of electrons to rapidly permeate through barriers that are just a few atoms thick, potentially advancing the speed, energy consumption, and density of future electronic devices.
Creating the future framework information storage
To conduct their research, the team utilised a 2D material – a one atom thick layer of nitrogen and boron – which was organised in a repetitive hexagonal structure, which they were able to break the symmetry of by assembling two such layers artificially.
Shalom said: “In its natural three-dimensional state, this material is made up of a large number of layers placed on top of each other, with each layer rotated 180 degrees relative to its neighbours (antiparallel configuration). In the lab, we were able to artificially stack the layers in a parallel configuration with no rotation, which hypothetically places atoms of the same kind in perfect overlap despite the strong repulsive force between them (resulting from their identical charges).
“In actual fact, however, the crystal prefers to slide one layer slightly in relation to the other, so that only half of each layer’s atoms are in perfect overlap, and those that do overlap are of opposite charges – while all others are located above or below an empty space – the centre of the hexagon. In this artificial stacking configuration, the layers are quite distinct from one another. For example, if in the top layer only the boron atoms overlap, in the bottom layer, it’s the other way around. Together we established a deep understanding of why the system’s electrons arrange themselves just as we had measured in the lab. Thanks to this fundamental understanding, we expect fascinating responses in other symmetry-broken layered systems as well.”
Maayan Wizner Stern, the PhD student who led the study, explained: “The symmetry breaking we created in the laboratory, which does not exist in the natural crystal, forces the electric charge to reorganise itself between the layers and generate a tiny internal electrical polarisation perpendicular to the layer plane. When we apply an external electric field in the opposite direction, the system slides laterally to switch the polarisation orientation. The switched polarisation remains stable even when the external field is shut down. In this, the system is similar to thick three-dimensional ferroelectric systems, which are widely used in technology today.”
“The ability to force a crystalline and electronic arrangement in such a thin system, with unique polarisation and inversion properties resulting from the weak Van der Waals forces between the layers, is not limited to the boron and nitrogen crystal,” adds Shalom. “We expect the same behaviours in many-layered crystals with the right symmetry properties. The concept of interlayer sliding as an original and efficient way to control advanced electronic devices is very promising, and we have named it Slide-Tronics”.
Maayan Vizner Stern concluded: “We are excited about discovering what can happen in other states we force upon nature and predict that other structures that couple additional degrees of freedom are possible. We hope that miniaturisation and flipping through sliding will improve today’s electronic devices, and moreover, allow other original ways of controlling information in future devices. In addition to computer devices, we expect that this technology will contribute to detectors, energy storage and conversion, interaction with light, etc. Our challenge, as we see it, is to discover more crystals with new and slippery degrees of freedom.”
