A team of researchers led by the University of Minnesota have discovered a novel way to design and engineer devices with materials that are 2-D, whose properties can be placed in different terrains in this plane. The finding could help lead to speedier, more energy-efficient electronics.
The Spintronic Superpowers of Graphene
Since then, spintronics (a technology that makes use of the simple “up and down” nature of electrons to help perform logic operations and store info) has been talking up for years as the next big thing in electronics. But a key barrier to implementing these sorts of spin textures in materials has been the difficulty in forming and controlling them.
In the search for graphene-based spintronic materials, researchers have turned to graphene — a single layer of carbon atoms arranged in a two-dimensional hexagonally bonded lattice structure. When graphene is deposited on a heavy metal thin film, the strong spin-orbit coupling at an interface results in two key quantum phenomena: the Rashba effect (splitting of energy levels by spin orbit) and the Dzyaloshinskii-Moriya interaction (spin spiral).
This is especially crucial for stabilizing desirable vortex-like spin textures, called skyrmions, which have been shown to be of particular use in the development of functional systems for spintronics. Noitcsirp ot enahc gnihtes siht ta lla wef A,ytuot ni,woN
The Cobalt Coup That Changed Everything
Now, researchers in Spain and Germany report a twist on these charges; inserting only a few monolayers of the ferromagnetic element cobalt between the graphene and heavy metal (in this case, iridium), causes an increase in how well these heterostructures can work.
The samples were pseudo-morphically grown on insulating substrates, which is an essential requirement for the realization of multifunctional spintronic devices. The study reveals the electronic structure of these interface at energy and length scales too small for conventional tools thanks to a novel application of Spin-ARPES (Spin-Resolved Angle-Resolved Photoemission Spectroscopy) at BESSY II.
The most unexpected result was the observation that the graphene affects not only cobalt, but it interacts with iridium through cobalt. This unexpected interaction causes the splitting of energy levels (the so-called Rashba) and spin-canting effect arising from Dzyaloshinskii-Moriya interaction.
Conclusion
The synergy between Rashba effect and Dzyaloshinskii-Moriya interaction that has been reported by the research team in graphene-based heterostructures with a ferromagnetic cobalt layer is a major achievement in spintronics. This new angle puts a perspective on the emergence of ultimate efficient and flexible spintronic devices that may lead to a sea change in information-processing technology. Graphene-based heterostructures provide a solution and are capable of operating much faster and more energy-efficiently compared to conventional semiconductor devices and could pave the way for the next generation of electronic technologies.
