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Tuesday, 11 March 2014

Graphene nanoislands edges filter electrons depending on their spin

A work in Physical Reviews Letters, led by Dr. Aitor Mugarza, explains how the edges of graphene nanoislands can become an insurmountable wall only for electrons with a given spin. Different atomic configurations at the edges present different interference patterns.

Understanding how electrons interact with the edges of graphene islands is essential to keep advancing towards its novel industrial applications. A work published in Physical Reviews Letters shows that the edges of graphene nanoislands grown on Ni(111) act as spin filters, meaning that electrons are scattered or manage to pass through the island depending on their spin. The study also highlights the role of the atomic structure of the edges: Different edge structures present different electron interference patterns when analyzed with a scanning tunneling microscope (STM) operated at 5 K in ultrahigh vacuum. The authors attribute this particular scattering behavior to how the C atoms of the graphene nanoislands interact with the underlying Ni atoms, which spin-polarize graphene electrons and stabilize edges with different atomic configuration.

The investigation, led by Dr. Aitor Mugarza, head of the Atomic Manipulation and Spectroscopy Group at ICN2, elucidates the complex scattering properties of graphene-metal interfaces, which had not been addressed with a two-dimensional beam of electrons parallel to the graphene-metal interface. The results are important for the control of electron transport and quantum confinement in lateral graphene junctions with spin-polarized electrodes.

Article Reference:

A. Garcia-Lekue, T. Balashov, M. Olle, G. Ceballos, A. Arnau, P. Gambardella, D. Sanchez-Portal, and A. Mugarza. Spin-Dependent Electron Scattering at Graphene Edges on Ni(111) Phys. Rev. Lett. 112, 066802 – Published 14 February 2014 DOI: http://dx.doi.org/10.1103/PhysRevLett.112.066802