Physicists from The University of Manchester and The University of Sheffield have discovered that when two atomically thin (two-dimensional) materials like graphene are placed on top of each other like a ‘Lego’ tower, their properties change and a material with novel hybrid properties emerges, paving the way for design of new materials and nano devices.

This happens without the two atomic layers physically meeting, nor through a chemical reaction, but by attaching the layers to each other via a weak so called van der Waals interaction - similar to how a sticky tape attaches to a flat surface.

In the ground-breaking study published in Nature, scientists have also found that the properties of the new hybrid material can be precisely controlled by twisting the two stacked atomic layers, opening the way for the unique design of new materials and electronic devices for future technologies.

The idea to stack layers of different materials to make so-called heterostructures goes back to the 1960s, when semiconductor gallium arsenide was researched for making miniature lasers – which are now widely used.

Today, heterostructures are common and are used very broadly in semiconductor industry as a tool to design and control electronic and optical properties in devices.

More recently in the era of atomically thin two-dimensional (2D) crystals, such as graphene, new types of heterostructures have emerged, where atomically thin layers are held together by relatively weak van der Waals forces.

The new structures nicknamed ‘van der Waals heterostructures’ open a huge potential to create numerous designer-materials and novel devices by stacking together any number of atomically thin layers. Hundreds of combinations become possible otherwise inaccessible in traditional three-dimensional materials, potentially giving access to new unexplored optoelectronic device functionality or unusual material properties.