Researchers report novel method for revealing and characterizing the spin-polarization of edge states in graphene nanoribbons

A team of scientists, led by David Serrate, CSIC scientist at the Instituto de Nanociencia y Materiales de Aragón, INMA (a joint institute of the CSIC and the University of Zaragoza), has imaged for the first time the magnetic behavior of a graphene nanostructure. The team has not only revealed the magnetic state of narrow graphene ribbons (~2 nm), but has also shown the method they developed to magnetically characterize any planar nanographene.

Starting with a specifically designed organic precursor, the researchers synthesized the ribbons directly onto a magnetic surface, obtaining atomically precise edges that contain an alternating sequence of zig-zag graphene segments. This geometry strongly confines the graphene electron cloud around the edge, which causes the instability responsible for the intrinsic magnetism of the graphene nanostructure –a remarkable fact taking into account that the ribbon is formed just by non-magnetic carbon and hydrogen atoms.


The detection method of choice was the spin-polarized STM technique, a type of microscopy which captures images of the current flowing between the sample and an atomically sharp needle able to count how many electrons travel with one or another magnetization. 

Graphene nanostructures are a promising platform for engineering electronic states with tailored magnetic and quantum properties. Bottom-up synthesis techniques have successfully produced atomically perfect structures with controlled size, shape and edge topology. Their versatility, low production cost, and natural length scale right within the quantum realm, makes them an excellent alternative to silicon based electronic devices. Future research in this line will tackle the challenge of preserving the quantum properties and enhancing the quantum coherence of this kind of ribbons. 

"In a few years from now we shall be able to provide the proof of concept of a self-assembled organic quantum bit… hopefully!", says David Serrate, staff scientist of the Instituto de Nanociencia y Materiales de Aragón and responsible of the project.

The team, which included researchers from INMA, DIPC (Donostia International Physics Center) CINN (Nanomaterials & Nanotechnology Research Center, CSIC University of Oviedo), CFM (Center for Materials Physics, CSIC-University of the Basque Country) and CIQUS (Centro Singular de investiguación en Química Biológica y Materiales Moleculares, University of Santiago de Compostela), performed the whole experimental work at the Laboratorio de Microscopías Avanzadas (LMA), in Zaragoza, a Singular Scientific-Technical Infrastructure (ICTS) of the University of Zaragoza linked to the Aragon Nanoscience and Materials Institute (INMA). 

Posted: Oct 26,2023 by Roni Peleg