Researchers recently made a groundbreaking discovery that challenges our understanding of magnetic materials. They found that chromium selenide (Cr₂Se₃), which is typically considered non-magnetic in its bulk form, becomes magnetic when reduced to just a…
Magnetic Marvels: Thin Films Transform Electronics with Spintronics
Scientists have made a groundbreaking discovery that challenges our understanding of magnetism. Specifically, they’ve found a way to turn a non-magnetic material into a magnet simply by making it into an incredibly thin film. This incredible feat opens doors to faster, smaller, and more efficient electronics. Hence, it all starts with a material called chromium selenide (Cr₂Se₃).
From Non-Magnetic to Magnetic: The Cr₂Se₃ Story
Unlike traditional magnets, Cr2Se3 exhibits magnetism even at the monolayer (ML) level—a single layer of atoms! This is surprising because the Mermin-Wagner theorem predicts that isotropic 2D magnets shouldn’t exist at room temperature. However, Cr2Se3’s anisotropy (the difference in properties along different directions) allows it to defy this rule. Moreover, opening doors for exciting new technologies.
Traditionally, bulk chromium selenide (Cr₂Se₃) isn’t magnetic. However, an international team of researchers discovered something astonishing. When they thinned Cr₂Se₃ down to atomically thin film layers, it magically transformed into a ferromagnetic material! This means its magnetic moments align in the same direction, creating a strong magnetic field. This directly contradicts existing theories predicting that such behavior is impossible in 2D materials. The team used a technique called molecular beam epitaxy to grow these ultra-thin films on graphene.
Thickness Matters: The Dance of Magnetism
The magnetic behavior of Cr2Se3 is incredibly sensitive to its thickness. Interestingly, researchers have observed increases and decreases in the Curie temperature (Tc). The temperature at which a material loses its magnetic properties depends on the number of layers. One study even showed a dramatic increase in Tc from 160 K to 280 K as the thickness decreased! These findings highlight the complexity and potential of manipulating the magnetic behavior through nanoscale control.
Shrinking and Strengthening: The Thinner, the Better
Further, the researchers found that the thinner the Cr₂Se₃ film, the stronger its magnetic properties became! This is completely counterintuitive to established understanding. This unexpected result opens exciting possibilities for smaller and more powerful electronic components. Imagine the implications for smartphones and data storage!
Unveiling the Mystery: Electrons and the Unexpected
So, what’s the secret behind this magnetic transformation? Through advanced techniques like micro-ARPES (angle-resolved photoemission spectroscopy), the researchers discovered that electrons injected from the graphene substrate are key. These electrons interact with the Cr₂Se₃, triggering the ferromagnetic behavior. This finding provides a crucial explanation for the observed phenomenon.
Understanding Ferromagnetism
Traditionally, scientists believed that thermal fluctuations would prevent magnetic order in two-dimensional materials. However, this research proves otherwise. It shows how superconductivity can exist at extremely thin film layers and even emphasizes increased transition temperatures as thickness decreases. Researchers discovered that conduction electrons from graphene play a crucial role in making these ultra-thin films behave magnetically.
When grown on insulating substrates, monolayer Cr2Se3 behaves as an antiferromagnetic (AFM) insulator. However, surprisingly, when grown on a conductive substrate like highly oriented pyrolytic graphite (HOPG), it transforms into a ferromagnetic (FM) metal! This demonstrates the crucial role of the substrate-material interaction in shaping the magnetic behavior of the material.
The Future is Spintronic: Smaller, Faster, More Efficient Electronics
This discovery is huge for the field of spintronics. While current electronics rely on the electrical charge of electrons, spintronics also uses their magnetic spin. This dual approach opens the door to even more efficient and powerful electronics. The possibilities are endless: faster processors, more efficient energy storage, and even advancements in quantum computing. The researchers plan to use a new, state-of-the-art facility to further their research with improved resolution.
The unique properties of Cr2Se3 hold immense potential for future technologies. Imagine ultra-thin, energy-efficient magnetic devices for applications like spintronics and quantum computing. Cr2Se3’s ability to switch between AFM and FM states, depending on the substrate, also opens doors for highly controllable magnetic switches. However, further research is needed to harness this potential fully.
Reference
- Chuang, C., Kawakami, T., Sugawara, K., Nakayama, K., Souma, S., Kitamura, M., Amemiya, K., Horiba, K., Kumigashira, H., Kremer, G., Fagot-Revurat, Y., Malterre, D., Bigi, C., Bertran, F., Chang, F. H., Lin, H. J., Chen, C. T., Takahashi, T., Chainani, A., & Sato, T. (2025). Spin-valley coupling enhanced high-TC ferromagnetism in a non-van der Waals monolayer Cr2Se3 on graphene. Nature Communications, 16(1). https://doi.org/10.1038/s41467-025-58643-3
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Neha Adikane holds a Master’s degree in Environmental Science from Pune University, bringing a unique blend of scientific expertise and creative writing skills to her craft. She specializes in creating engaging, insightful, and impactful content across various niches. With a passion for translating complex ideas into simple, relatable narratives, she excels at crafting blogs, articles, website content, and social media posts that captivate readers and drive engagement. Neha’s background in environmental science adds depth to her writing, allowing her to effectively cover topics related to sustainability, eco-awareness, and scientific innovations.
