2D materials with a twist

Welcome to the world of twistronics – electronics with a twist.

There is increasing interest in the potential of the ultimate 2D materials (those consisting of just a single layer of atoms) because of their impressive properties such as high conductivity, flexibility and strength. Think applications in lasers, sensors and the like.

When a sheet of such 2D material is placed over another and slightly rotated, the twist can radically change the bilayer material’s properties and lead to exotic physical behaviours.

Now researchers led by Finland’s Aalto University say they have taken an important step forward by developing a way to make these twisted layers on scales that are large enough to be useful.

Their new method for transferring single-atom layers of molybdenum disulfide (MoS2), described in a paper in the journal Nature Communications, allows them to precisely control the twist angle between layers with up to a square centimetre in area, they say.

“Our demonstrated twist method allows us to tune the properties of stacked multilayer MoS2 structures on larger scales than ever before,” says Luojun Du, one of the lead authors. “The transfer method can also apply to other two-dimensional layered materials.”

Du and colleagues say previous research has demonstrated that it is possible to fabricate the required twist angle, but the sample size has usually been less than the width of a human hair. Larger few-layer films have also been fabricated, but their interlayer twist angle is random.