Graphene Nanoribbons Reach Out to the Molecular World

Researchers from CIC nanoGUNE, Materials Physics Center (CFM), Donostia International Physics Center (DIPC), and Center for Research on Biological Chemistry and Molecular Materials (CiQUS) have developed the smallest magnetic device contacted, made of one molecule.

Scanning Tunneling Microscopy image of the new molecular device and its graphene nanoribbons contacts. (Credit: nanoGUNE)

A single molecule can act as the tiniest electronic part of an electronic system. Keeping this principle in mind, the research team in the field of molecular electronics has strived in the last years to devise innovative techniques that bring closer the much-awaited aim of utilizing molecules as electronic logic components.

One of the most recent steps forward is appearing on peer-reviewed journal Science Advances, thanks to a new association between physicists from CIC nanoGUNE, Materials Physics Center (CFM, CSIC-UPV/EHU), Donostia International Physics Center (DIPC), and synthetic chemists from CiQUS (Center for Research on Biological Chemistry and Molecular Materials at the University of Santiago de Compostela). This is a new breakthrough that has made it possible to contact a single-molecule magnetic device for the first time.

The idea is fascinating: to store information into a single molecule and read it. We have known for long time how to make the molecules, but we could never wire them into a circuit until now.

Nacho Pascual, Ikerbasque Professor and Leader of the Nanoimaging Group, nanoGUNE

In order to achieve this objective, the researchers developed graphene narrow stripes, intending to use them as electrical wires; a technique was also developed by the team to precisely contact the molecule at predefined places.

We found that the contact to the molecule crucially affects how the molecular device behaves. This discovery has made us direct the contacting step with atomic precision technologies.

Jingcheng Li, First Author of the Article

With regards to the molecule creation process, the researchers, in this case, used a chemical technique based on guided chemical reactions over a metallic surface.

The creation of the molecular device is simple”, explains CiQUS team leader, Diego Peña, “We designed and synthetized the building blocks with ‘glue-like’ chemical terminations at the points where contacts are to be created; from then on, nature does the rest of the job for us,” he jokes.

To demonstrate the process, the scientists have provided a very visual metaphor, “We can see it as a molecular LEGO,” they said. In words of Dr. Pascual, “We are learning how to use nature’s laws for assembling molecules into more complex nanostructures,” he claims.

Scanning Tunneling Microscopy (STM) is a highly sophisticated technique used to visualize molecules and atoms and to determine their behavior. Using the STM method, the authors showed the working function of the molecular device. With the help of this tool, they were able to prove under which conditions the magnetic data stored in the molecule could withstand the contact, thus paving the way to develop new materials for efficient electronics.

The study has been realized in the framework of a Spanish collaborative research consortium named FunMolDev (acronym of Functional Molecular Devices), funded by the Government of the Basque Autonomous Community, the Spanish Ministry for the Economy and Competitiveness, the Xunta de Galicia, and the European Union.

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