Two-dimensional anion-rich NaCl<sub>2</sub> crystal under ambient conditions.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39774980.
- Also identified by DOI 10.1038/s41467-024-55512-3 and PMC identifier 11707346.
- Licence recorded as CC BY-NC-ND.
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Abstract
The two-dimensional (2D) "sandwich" structure composed of a cation plane located between two anion planes, such as anion-rich CrI<sub>3</sub>, VS<sub>2</sub>, VSe<sub>2</sub>, and MnSe<sub>2</sub>, possesses exotic magnetic and electronic structural properties and is expected to be a typical base for next-generation microelectronic, magnetic, and spintronic devices. However, only a few 2D anion-rich "sandwich" materials have been experimentally discovered and fabricated, as they are vastly limited by their conventional stoichiometric ratios and structural stability under ambient conditions. Here, we report a 2D anion-rich NaCl<sub>2</sub> crystal with sandwiched structure confined within graphene oxide membranes with positive surface potential. This 2D crystal has an unconventional stoichiometry, with Na:Cl ratio of approximately 1:2, resulting in a molybdenite-2H-like structure with cations positioned in the middle and anions in the outer layer. The 2D NaCl<sub>2</sub> crystals exhibit room-temperature ferromagnetism with clear hysteresis loops and transition temperature above 320 K. Theoretical calculations and X-ray magnetic circular dichroism (XMCD) spectra reveal the ferromagnetism originating from the spin polarization of electrons in the Cl elements of these crystals. Our research presents a simple and general approach to fabricating advanced 2D unconventional stoichiometric materials that exhibit half-metal and ferromagnetism for applications in electronics, magnetism, and spintronics.