Magnetic graphene could boost generation of spin currents

A team of researchers from The University of Groningen and Columbia University have found that 2D spin-logic devices could benefit from magnetic graphene that can efficiently convert charge to spin current, and can transfer this spin-polarization over long distances.

Graphene is known amongst 2D materials for transporting spin information, but cannot generate spin current unless its properties are modified – conventionally cobalt ferromagnetic electrodes are used for injecting and detecting the spin signal.

If graphene can be given magnetic properties, it could favor the passage of one type of spin, tipping the balance between spin-up and spin-down electron populations, creating a spin-polarized current.

Key to the discovery is the proximity of bilayer graphene to a CrSBr antiferromagnet interlayer.

“We detect an exceptionally large spin-polarization of conductivity of 14% in the magnetic graphene that is also expected to be efficiently tunable by a transverse electric field,” said Groningen researcher Talieh Ghiasi.

Unavoidable heat dissipation is ususally a problem, but can sometimes be a benefit.

“We observe that the temperature gradient in the magnetic graphene due to the Joule heating is converted to spin current,” said Ghiasi. “This happens by the spin-dependent Seebeck effect that is also observed in graphene for the first time in our experiments.” says Ghiasi.

Spin transport in graphene is sensitive to the magnetic behavior of the outer-most layer of the neighboring antiferromagnet. “This implies that such spin transport measurements enable read-out of the magnetization of a single atomic layer,” according to the university. “Thus, the magnetic graphene-based devices not only address the most technologically-relevant aspects of magnetism in graphene for the 2D memory and sensory systems, but also provide further insight into the physics of magnetism.”