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Guidelines for Selecting Interlayer Spacers in Synthetic 2D-Based Antiferromagnets from First-Principles Simulations.
Ramón Cuadrado1,2, Miguel Pruneda1
1Catalan Institute of Nanoscience and Nanotechnology - ICN2, CSIC and BIST, Campus UAB, 08193 Bellaterra, Spain.
Nanomaterials (Basel, Switzerland)
|December 15, 2019
Summary
Researchers studied graphene spacers between cobalt and iron layers to create antiferromagnetic materials. Ultrathin graphene spacers are crucial for robust magnetic coupling, unlike thicker layers or hexagonal boron nitride.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Spintronics
Background:
- Recent synthesis of graphene-based ultrathin heterostructures involving cobalt (Co) and iron (Fe) has opened new avenues for antiferromagnetic materials.
- Understanding the role of spacer materials is critical for controlling magnetic coupling in these advanced heterostructures.
Purpose of the Study:
- To analyze the effect of different spacer materials (graphene and hexagonal boron nitride) on the magnetic properties of Co/Fe heterostructures.
- To investigate the geometric, electronic, and magnetic properties of these systems using first-principles calculations.
Main Methods:
- Density functional calculations were employed to study Co monolayers on Ir(111) coupled to Fe through varying numbers of graphene layers (n=1, 2, 3) or hexagonal boron nitride (h-BN).
- Calculations included analysis of local atomic arrangements, Moiré patterns, and magnetic exchange interactions (JCo-Fe) by aligning Fe/Co layers parallel and antiparallel.
- Fully relativistic calculations were used to determine magnetic anisotropy energies.
Main Results:
- Graphene spacers mediate robust antiferromagnetic superexchange coupling between Fe and Co layers via hybridization of carbon pz orbitals with Fe/Co 3d states.
- This magnetic coupling is significantly suppressed with multilayered graphene spacers, highlighting the importance of ultrathin spacers.
- Hexagonal boron nitride also mediates coupling through pz orbitals but shows a larger contribution from local ferromagnetic interactions.
- All configurations exhibit an out-of-plane magnetic easy axis with anisotropy energies ranging from 1 to 4 meV.
Conclusions:
- Ultrathin (monolayer) graphene spacers are essential for designing synthetic graphene-based antiferromagnets due to efficient magnetic coupling.
- Multilayered graphene spacers critically reduce the magnetic coupling between ferromagnetic Fe and Co layers.
- Hexagonal boron nitride offers an alternative but results in a different magnetic coupling profile compared to graphene.
Keywords:
2d materialsdensity functional theoryelectronic structureexchange interactionsmagnetic anisotropymagnetic materialsMore Related Videos
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