Superatom Distortion Induces Triferroicity and Spin Splitting in Two-Dimensional Antiferromagnets

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Two-dimensional (2D) materials offer potential for multifunctional devices.
• Achieving triferroicity (ferroelectricity, ferroelasticity, and specific magnetic order) simultaneously in 2D materials is challenging.
• Conventional atomic structures struggle to host multiple ferroic orders concurrently.

Purpose of the Study:

• To propose a general strategy for achieving concurrent ferroelectricity, antiferromagnetic (AFM) spin splitting, and ferroelasticity in 2D materials.
• To demonstrate this strategy using superatoms incorporated into 2D lattices.
• To identify a representative material and explore its magnetoelectric coupling.

Main Methods:

• Utilized first-principles calculations to investigate material properties.
• Focused on strong p-d orbital hybridization within superatoms to induce symmetry breaking.
• Analyzed the Jahn-Teller effect in the NbB₁₂H₆ monolayer as a specific example.

Main Results:

• Demonstrated that superatom incorporation enables the coexistence of ferroelectricity, AFM spin splitting, and ferroelasticity.
• Identified NbB₁₂H₆ monolayer as a material exhibiting these properties due to Jahn-Teller driven distortions.
• Confirmed robust magnetoelectric coupling through deterministic reversal of AFM spin splitting by ferroelectric polarization.

Conclusions:

• Superatom assembly is a powerful strategy for designing 2D multiferroics.
• This approach facilitates the control of spin degrees of freedom in multifunctional materials.
• The framework is extendable to a wide range of materials by altering metal components or superatomic motifs.