Monolayer M₂X₂O as potential 2D altermagnets and half-metals: a first principles study

Area of Science:

• Materials Science
• Condensed Matter Physics
• Solid State Chemistry

Background:

• Development of novel two-dimensional (2D) magnetic states is crucial for advancing spintronic devices and understanding 2D magnetic physics.
• Existing research focuses on identifying materials with unique magnetic properties for technological applications.

Purpose of the Study:

• To investigate the magnetic and electronic properties of dynamically stable and exfoliable M2X2O compounds.
• To identify potential 2D altermagnets, half-metals, and topological materials for spintronic and fundamental physics applications.

Main Methods:

• Computational examination of magnetic and electronic properties of 20 M2X2O compounds (M = Ti-Ni; X = S-Te; excluding Co2Te2O).
• Analysis of M-3d orbital splittings governed by [X4O2]-D2 and [M4]-D4 crystal fields.
• Investigation of kinetic and superexchange mechanisms driving magnetic ordering.

Main Results:

• Identified antiferromagnetic (AFM) and ferromagnetic orderings in various M2X2O compounds.
• Confirmed all AFM M2X2O as 2D altermagnets and several as 2D half-metals (Ti2Se2O, Ti2Te2O, Co2S2O, Co2Se2O).
• Discovered tunable altermagnetic splitting in Ti2S2O/Cr2Te2O and symmetry-protected splitting in V2X2O.
• Highlighted potential 2D altermagnetic Weyl semimetals (Fe2S2O/Fe2Se2O), nodal-loop half-metals (Ti2Se2O), and half-semimetals (Ti2Te2O).

Conclusions:

• Monolayer M2X2O compounds offer promising candidates for low-dimensional spintronic devices due to their altermagnetic and half-metallic properties.
• These materials expand the platform for exploring 2D altermagnets and novel topological physics.
• The findings provide a theoretical foundation for designing next-generation spintronic materials and understanding complex magnetic phenomena.