This is the structure of regular old 2D graphene. image: Flickr/Argonne National Laboratory
Remember graphene, that super-strong, super-conductive two-dimensional material that’s poised to make tiny transistors, flexible smartphones, and next-generation condoms for Bill Gates? It looks like it’s got competition in the wonder material stakes, as a team of scientists has discovered what’s being touted as graphene's 3D cousin.
Researchers led by physicist Yulin Chen from Oxford University discovered a type of sodium bismuthate (Na3Bi) in a quantum matter form. It’s called a “three-dimensional topological Dirac semi-metal,” or 3DTDS, and apparently it’s something scientists have been looking for since they first got so excited about graphene.
Where graphene is two-dimensional—it’s a single sheet of carbon atoms—this new material is three-dimensional. That’s important, the researchers explained in a report published in Science, because it “makes it possible to realize the many exciting phenomena and applications of graphene in 3D materials,” as well as offering a few unique properties of its own.
While people have theorised about the existence of 3DTDS states before, this is the first practical confirmation that they do in fact exist. Chen explained the technical properties in a release:
You can think of the electronic structure of the 3DTDS as being rather like that of the graphene–the so called ''Dirac cone'' where electrons collectively act as if they forget their mass–but instead of flowing masslessly within a single sheet of atoms, the electrons in a 3DTDS flow masslessly along all directions in the bulk.
Because of this, there’s hope that a 3DTDS could be easier to work with than graphene in certain applications where thinness isn't a benefit, and easier to produce on a large scale.
They’re also of interest because, when it comes to magnetoresistance—“how its electrical resistance changes when a magnetic field is applied”—they show a lot more change than other materials. As magnetoresistance is used in reading hard drive data, that suggests one key potential application.
“With this much larger effect we could make a hard drive that is higher intensity, higher speed, and lower energy consumption—for example turning a 1 terabyte hard drive into a drive that can store 10 terabytes within the same volume,” explained Chen.
Unfortunately, however, it doesn’t look like sodium bismuthate is the 3DTDS to make good on those plans, because it’s apparently too unstable to use in a device without “proper packaging.”
But now the the existence of one such compound has been demonstrated, it opens the door for scientists to search for other new, exotic materials. Graphene might have a head start, but the race is still on to track down wonder materials that tick all the boxes.