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Advancements in Spintronics Through Graphene and Cobalt Heterostructures
Spintronics, a technology leveraging the intrinsic spin of electrons for information processing and storage, is gaining traction due to its potential for enhancing the speed and energy efficiency of devices compared to traditional semiconductor technologies. Nevertheless, the creation and control of spin textures in materials remain challenging obstacles in the field.
Among the materials being explored for their spintronic capabilities, graphene—a two-dimensional arrangement of carbon atoms—stands out. Graphene is often utilized in conjunction with thin layers of heavy metals, laying the groundwork for exciting quantum phenomena.
At the junction where graphene meets heavy metal, notably iridium, strong spin-orbit coupling is established. This interaction results in various quantum mechanical effects, including the Rashba effect, which causes energy levels to split, and the Dzyaloshinskii-Moriya interaction, which leads to a twisting in the alignment of spins. The latter is essential for stabilizing skyrmions, intricate vortex-like spin configurations that show promise for spintronic applications.
Recent research by a collaborative team from Spain and Germany has revealed that the introduction of several monolayers of cobalt—a ferromagnetic element—between graphene and the heavy metal significantly strengthens these effects. Their studies were conducted on insulating substrates, a vital aspect for developing multifunctional spintronic devices that capitalize on these properties.
The findings of this research are detailed in a publication featured in ACS Nano.
“At BESSY II, we conducted a detailed analysis of the electronic structures present at the interfaces of graphene, cobalt, and iridium,” stated Dr. Jaime Sánchez-Barriga, a physicist involved with the project. He pointed out that a surprising discovery was made: graphene interacts not just with cobalt but also through cobalt with iridium.
“The ferromagnetic cobalt layer enhances the interaction between graphene and iridium, further increasing the energy level splitting,” Sánchez-Barriga explained. He noted that the extent of spin canting—the twisting of spin orientations—can be adjusted by varying the number of cobalt monolayers, with three layers being the optimal configuration.
This conclusion is supported by experimental data and advanced theoretical models based on density functional theory, showcasing how the two quantum effects not only coexist but also amplify one another in this context.
Professor Oliver Rader, leading the “Spin and Topology in Quantum Materials” department at HZB, highlighted the importance of BESSY II’s specialized instruments for measuring photoemission with spin resolution (Spin-ARPES). He explained that the precision of these measurements allowed the team to effectively identify the underlying sources of the spin canting phenomena more accurately than ever before.
Such advanced capabilities are rare and available only at a few research centers around the globe. The promising results indicate that graphene-based heterostructures could play a pivotal role in the development of next-generation spintronic devices, potentially transforming the landscape of electronic technology.
More information: Beatriz Muñiz Cano et al, Rashba-like Spin Textures in Graphene Promoted by Ferromagnet-Mediated Electronic Hybridization with a Heavy Metal, ACS Nano (2024). DOI: 10.1021/acsnano.4c02154
Citation: Analysis of heterostructures for spintronics shows how two desired quantum-physical effects reinforce each other (2024, September 20) retrieved 20 September 2024 from https://phys.org/news/2024-09-analysis-heterostructures-spintronics-desired-quantum.html
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phys.org