Thin magnetic crystals are path to ferromagnetic graphene

Chromium triiodide (CrI₃) crystals were identified as a promising platform for studying how magnetism can enhance electronic behaviors in materials that are only a few atoms thick. Development of such ultra-thin magnetic materials may be crucial for continued advancement in miniaturization and  performance enhancement of electronic devices.

The combined experimental and theoretical study, enabled by growth of large single crystals, revealed the detailed atomic arrangement and magnetic behavior of CrI₃. The material is made up of three-atom-thick layers, which are weakly bound to one another. As a result, the material is easily peeled, or cleaved, into very thin sheets. Calculations show the strength of the interlayer bonding is similar to that of graphite, which can be easily cleaved into graphene, a single layer of carbon atoms of great interest for electronics applications. At low temperatures, the magnetic moments of the chromium atoms align with a strong preference to be directed perpendicular to the layers. This ferromagnetism is favored even in single CrI₃ layers, enabling magnetism to participate in the electronic functionality of very thin materials.

 

M. A. McGuire, H. Dixit, V. R. Cooper, and B. C. Sales, “Coupling of crystal structure and magnetism in the layered, ferromagnetic insulator CrI₃,” Chemistry of Materials (2015).  DOI: 10.1021/cm504242t.

 

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