Graphene, a one-atom thick lattice of graphite, is a synthetic material with diverse applications ranging from solar cells to diagnostics.
It is simple to synthesise and deploy, and allows scientists to manipulate its properties at the atomic level. Its greatest advantage is that it is much more electrically conductive than copper or silver at room temperature.
Its magnetic capability, however, is nearly unexplored. A paper published online in Nature on April 28 announced a significant development that could change this.
Researchers from the Universidad Autonoma de Madrid (UAM), Spain, have demonstrated how graphene could facilitate the formation of a magnetic field under certain conditions.
This development could potentially open the floodgates on graphene’s use in computers, which use magnetic fields to store information on hard-drives.
Manuela Garnica and Sara Barja from UAM first grew a graphene sheet on a base made of the element ruthenium (Ru).
Next, they evaporated organic molecules called tetracyano-p-quinodimethane (TCNQ) on the graphene, which gathered on the layer in a condensed manner.
Ms. Garnica, a PhD student, said in an email to this Correspondent, “Graphene acts as a separating layer between the ruthenium and TCNQ molecules,” preventing TCNQ from bonding with the Ru base. Because Ru is a good electrical conductor, it has a lot of free and highly mobile electrons that move into the graphene layer, and then into the TCNQ layer.
The unique property of graphene to prevent bonding between two layers while allowing charge transfer between them allows the spins of electrons in the top layer to get aligned with those in the bottom. This alignment is called an antiferromagnetic coupling.
Once all electrons have the same spin, the system is said to have a magnetic field. This is the first time graphene has been shown to play a role in the creation of a magnetic field.
Such graphene-Ru arrangements can be used to align electrons with random spins to the same spin. This could find application in faster manipulation of digital information and their high-efficiency storage in computers, Ms. Garnica said.