Graphene-based heterostructures of the van der Waals class could be used to design ultra-compact and low-energy electronic devices and magnetic memories. This is what a paper published in the latest issue of the Nature Materials journal suggests. The results have shown that it is possible to perform an efficient and tunable spin-charge conversion in these structures and, for the first time, even at room temperature.
The work has been led by ICREA Prof. Sergio O. Valenzuela, head of the ICN2 Physics and Engineering of Nanodevices Group. The first authors are L. Antonio Benítez and Williams Savero Torres, of the same group. Members of the ICN2 Theoretical and Computational Nanoscience Group, as its head, ICREA Prof. Stephan Roche, also signed the paper. This study has been developed within the framework of the Graphene Flagship, a broad European Project in which researchers of the Catalan Institute of Nanoscience and Nanotechnology (ICN2), at the Universitat Autònoma de Barcelona campus, play a leadership role. The results complement recent researches carried out within this same initiative, such as the one published in 2019 in NanoLetters by scientists from the University of Groningen (RUG).
The electronics that use spin - a property of electrons - to store, manipulate and transfer information, called spintronics, are driving important markets, such as those of motion sensors and information storage technologies. However, the development of efficient and versatile spin-based technologies requires high-quality materials that allow long-distance spin transfer, as well as methods to generate and manipulate spin currents, i.e. electron movements with their spin oriented in a given direction.
The spin currents are usually produced and detected using ferromagnetic materials. As an alternative, spin-orbit interactions allow the generation and control of spin currents exclusively through electric fields, providing a much more versatile tool for the implementation of large-scale spin devices.
Graphene is a unique material for long distance spin transport. The present work demonstrates that this transport can be manipulated in graphene by proximity effects. To induce these effects, transition metal dichalcogenides have been used, which are two-dimensional materials as graphene. Researchers have demonstrated a good efficiency of spin-charge interconversion at room temperature, which is comparable to the best performance of traditional materials.
These advances are the result of a joint effort by experimental and theoretical researchers, who worked side by side in the framework of the Graphene Flagship. The outcomes of this study are of great relevance for the communities of spintronics and two-dimensional materials, as they provide relevant information on the fundamental physics of the phenomena involved and open the door to new applications.
About the ICN2
The Institut Català de Nanociència i Nanotecnologia (Catalan Institute of Nanoscience and Nanotechnology - ICN2) is devoted to the generation of knowledge, materials and devices in the broad fields of ICT, health, energy and the environment. Its expertise lies at the nanoscale, where new properties, interactions and ways to exploit them in everyday life are being discovered all the time. Among its goals is to bring together scientists from diverse backgrounds in the pursuit of better science, better training and better outreach to society, while also seeking out new ways to engage with local and global industry.
The institute was accredited as a Severo Ochoa Centre of Excellence in 2014, and the Spanish Ministry of Science, Innovation and Universities renewed this status in 2018. Among its trustees are the Generalitat of Catalonia, the Spanish National Research Council (CSIC) and the Universitat Autonoma de Barcelona (UAB), where it is based. The ICN2 is a CERCA Center and also one of the founding members of the Barcelona Institute of Science and Technology (BIST) and the Graphene Flagship.