Two-dimensional anion-rich NaCl₂ crystal under ambient conditions

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Two-dimensional (2D) "sandwich" structures with anion-rich compositions exhibit unique magnetic and electronic properties.
• These materials are crucial for next-generation microelectronic, magnetic, and spintronic devices.
• Fabrication of such 2D materials is challenging due to stoichiometric and stability limitations.

Purpose of the Study:

• To report the discovery and fabrication of a novel 2D anion-rich NaCl2 crystal.
• To investigate the structural, magnetic, and electronic properties of this unconventional material.
• To present a generalizable method for creating advanced 2D unconventional stoichiometric materials.

Main Methods:

• Synthesis of 2D NaCl2 crystals confined within graphene oxide membranes.
• Characterization of structural and magnetic properties, including X-ray magnetic circular dichroism (XMCD).
• Theoretical calculations to understand the origin of magnetism.

Main Results:

• Successful fabrication of a 2D anion-rich NaCl2 crystal with a molybdenite-2H-like structure.
• Observation of room-temperature ferromagnetism with a transition temperature above 320 K.
• Experimental and theoretical evidence confirming ferromagnetism originates from Cl electron spin polarization.

Conclusions:

• The 2D NaCl2 crystal demonstrates unconventional stoichiometry and room-temperature ferromagnetism.
• This work introduces a new class of 2D materials with potential for spintronic and electronic applications.
• The presented fabrication approach is simple and broadly applicable to advanced 2D materials.