by Joshua Green
If you were asked to name a 2D material a fair amount of you would scratch your heads in confusion or shout about how graphene is that ‘wonder material’. For starters, what is a 2D material? A 2D material is a sheet of a set dimension in one direction but only one (or a few more) layer-of-atom thick in the other direction. These types of materials are usually very hard to fabricate as the needs of precision and technology to obtain one atom thick material are high and expensive.
2D materials are unique in a sense that they have unique properties that, say, multiple layers of the material would have. Taking the example of graphene, which is essentially a 2D sheet of carbon atoms, scientists observe different properties that the material graphite (which is essentially hundreds of millions of layers of graphene) has. These 2D materials display exotic properties such as being semiconducting materials (things that can conduct electricity or be an insulator when specific requirements are met) when the bulk of 3D material do not. There are many more exotic properties and, also, many other 2D materials despite the massive popularity that graphene has in scientific circles and even popular culture.
Scientists have been able to create a new 2D material inside of a laboratory. These scientists from the University of Pennsylvania, have been able to create a 2D material called tungsten ditelluride. This material was created by using a technique called chemical vapour deposition (CVD for short). This involves heating up a tungsten chip inside a chamber whilst flowing through a vapour containing tellurium and altering many variables to get the desired 3-layer thick material. The research team comprised of Professor A.T Charlie Johnson, Professor James Kikkawa and graduate students Carl Naylor and William Parkin. This type of 2D material is actually as thick as 3 atoms, but can be considered a 2D material due to the extremely small scales more comparable to 2D than 3D bulk material.
The reason for the excitement of creating and experimenting with this tungsten ditelluride material is due to the properties it can exhibit as opposed to graphene. Although graphene remains a popular material many scientists claim that graphene is already becoming a ‘boring’ material to work with. Scientists desire materials that can do much more than just display the properties solely down to the material itself rather than properties related to the varying formation of the material itself. That’s where the 3-layer thickness of tungsten ditelluride becomes relevant. The three atoms involved with each ‘section’ of the layer can actually be rearranged in different combinations.
When the right configuration is found the material exhibits ‘topological electronic states’, which is a unusual property of a material, and one consequence of this is for a material like this tungsten ditelluride to conduct electricity only along the edges of the material rather than the centre of it.
There are many properties that a material can have with these states present. The varied properties that tungsten ditelluride can have, due to these ‘topological electronic states’ could lead to applications in quantum computing for reducing the error in measurements.