Graphene is made magnetic by intelligent nanostructuring
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, and responsible for this research, has imaged for the first time the magnetic behaviour of a graphene nanostructure. The work has been published in the prestigious journal Nature Communications, in which the authors have not only revealed the magnetic state of narrow graphene ribbons (~2 nm), but have also shown the method they have developed to magnetically characterise any planar nanographene.
The team, composed by researchers of 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). Starting by a specifically designed organic precursor, they synthesized the ribbons directly onto a magnetic surface, obtaining atomically precise edges that consist in 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 is the spin-polarized STM technique, a sort 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.
Images:
Illustration: Left: Topographic image of one the graphene nanoribbons on the magnetic GdAu2 monolayer, superimposed with its molecular structure. Right: Zoom in in one of the ribbons with the simultaneous magnetization map showing the spatially resolved spin density of the edge.
David Serrate, Principal Investigator.
Reference:
Detecting the spin-polarization of edge states in graphene nanoribbons. Nature Communications 14, 6677 (2023). DOI: 10.1038/s41467-023-42436-7
25-10-2023
