Graphene has a lot of useful properties, but magnetism isn’t one of them – at least, not usually. In a new study led by the University at Buffalo, researchers have managed to induce an “artificial magnetic texture” in the material, which could have major implications for the emerging field of spintronics.
Put simply, graphene is a lattice of carbon atoms that form a sheet only one atom thick. That means that electrons moving through the material are limited to two dimensions, which produces some intriguing electrical properties. It can be made into a semiconductor or superconductor, and it’s also a good conductor of heat. To top it off, graphene is extremely strong but lightweight and flexible.
One thing that’s not normally on this overachieving “wonder” material’s resumé is magnetism. But now, the researchers on the new study have added that as well. The team placed a 20-nanometer-thick magnet on top of a sheet of graphene. That may sound thin, but it’s more than 20 times thicker than the graphene itself.
“To give you a sense of the size difference, it’s a bit like putting a brick on a sheet of paper,” says Jonathan Bird, senior author of the study.
The team then placed eight electrodes around the graphene to measure how its conductivity changed in response to the magnet. To their surprise, the graphene exhibited an artificial magnetic texture that gave it similar magnetic properties to metals like iron or cobalt. This effect extended as far as a few microns away from the magnet itself, which doesn’t sound too far but is quite a hike on the microscopic scale.
Previous studies have magnetized graphene by exposing it to yttrium iron garnet, or by twisting two layers of the material to a “magic angle.”
The researchers say that further study will be needed to investigate just how this magnetism arises in the graphene. It’s likely, they say, to be the influence of either spin polarization or spin-orbit coupling, or both. These phenomena are related to the “spin” of particles, and commonly linked directly to a material’s magnetism. If so, magnetic graphene could turn out to be a boon for the emerging field of “spintronics,” which taps into this spin property to encode data more densely than current electronic devices.
“Independent of each other, graphene and spintronics each possess incredible potential to fundamentally change many aspects of business and society,” says Nargess Arabchigavkani, lead author of the study. “But if you can blend the two together, the synergistic effects are likely to be something this world hasn’t yet seen.”
The research was published in the journal Physical Review Letters.
Source: University at Buffalo