Though it is only comprised of a monolayer of carbon atoms arranged in a honeycomb pattern, graphene is a pretty impressive material. It’s incredibly strong, flexible, and light, making it widely desirable for a number of optical and mechanical applications. A group of researchers from Spain have opened up the number of possible applications for graphene by magnetizing it, which could be useful in the burgeoning field of spintronics. Rodolfo Miranda of IMDEA Nanoscience in Madrid was senior author on the paper, which was published in Nature Physics.
Though graphene is pretty great, it does have a couple of drawbacks. Graphene’s strength is partially reliant on the fact that the material does not have a bandgap, which limits its use as a semiconductor. It can be modified to have a bandgap, though it comes at the expense of the graphene’s integrity. However, graphene has never before been able to be magnetic, until Miranda’s group made a base layer of iridium crystal, with ‘islands’ of lead atoms in the middle, topped with a layer of graphene. This arrangement affects the electron’s orbit around the atom’s nucleus as well as its spin, which influences the magnetic force.
The interaction between the graphene and the iridium crystal creates a lower spin-orbit than what occurs where there are islands of lead. This two-dimensional layered structure creates a tremendous magnetic field, equivalent of 80 Tesla. For comparison, a refrigerator magnet has a magnetic field of about 0.005 Tesla.
”This spin-orbit interaction is a million times more intense than that inherent to graphene, which is why we obtain revolutions that could have important uses, for example in data storage," Miranda said in a press release.
In the sea of graphene (over an iridium crystal), electrons' spin-orbit interaction is much lower than that created by intercalating a Pb island. Credit: IMDEA Nanoscience/UAM/ICMM-CSIC/UPV-EHU
The researchers are able to manufacture the material in a way that preserves the integrity of the material, which will make it much easier to integrate into functional devices down the road.
"And, what is most important, under these conditions certain electronic states are topologically protected; in other words, they are immune to defects, impurities or geometric disturbances," Miranda explained. "If we compare it to traffic, in a traditional spintronic material cars circulate along a single-lane road, which make collisions more likely, whilst with this new material we have traffic control with two spatially separate lanes, preventing crashes."
Though the researchers aren’t currently able to control the spin-orbit of the electrons, this is the first glimpse that graphene could be useful in the field of spintronics. Spintronics is a portmanteau of "spin transport electronics” and is concerned with magnetic forces created by an electron’s spin. There is already considerable research with using spintronics to improve data processing in computers. If graphene could be used in this way, it would create a highly durable method of data storage. Miranda’s team is continuing their research, hoping to tame the spin of the electrons so that they can be controlled in a functional way.
[Hat tip: ScienceAlert]