Creation of High-Density Néel Skyrmions by Interfacial-Proximity Engineering

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Two-dimensional (2D) ferromagnets are key for miniaturized spintronic devices.
• Centrosymmetric structures in these materials suppress Dzyaloshinskii-Moriya interaction (DMI), preventing chiral spin texture formation.
• Stabilizing chiral spin textures like skyrmions is crucial for next-generation spintronics.

Purpose of the Study:

• To investigate tunable DMI via interface symmetry breaking in Fe3GeTe2/MoS2 van der Waals (vdW) heterostructures.
• To demonstrate the stabilization of Néel-type skyrmions under zero magnetic field.
• To explore the thickness-dependent behavior and interfacial origin of DMI-induced skyrmion stabilization.

Main Methods:

• Fabrication of Fe3GeTe2/MoS2 vdW heterostructures.
• Lorentz transmission electron microscopy (LTEM) for skyrmion nucleation and annihilation studies.
• Thickness-dependent measurements to determine proximity effect penetration depth.
• Micromagnetic simulations to correlate skyrmion behavior with interfacial DMI.
• First-principles calculations to elucidate the origin of DMI.

Main Results:

• Tunable DMI induced by interface symmetry breaking was achieved in Fe3GeTe2/MoS2 heterostructures.
• Néel-type skyrmions were stabilized at zero magnetic field, nucleating at 64 Oe and annihilating at 800 Oe.
• Skyrmion density peaked at ~30 nm Fe3GeTe2 thickness, decaying beyond ~60 nm, indicating a finite proximity effect penetration depth.
• Simulations confirmed the strong correlation between interfacial DMI and skyrmion field evolution.
• First-principles calculations attributed DMI to asymmetric charge redistribution and spin-orbit coupling at the interface.

Conclusions:

• Interface engineering is a viable strategy for stabilizing skyrmions in centrosymmetric vdW ferromagnets.
• The Fe3GeTe2/MoS2 system provides a thickness-tunable platform for controlling skyrmion density.
• This work paves the way for developing novel 2D spintronic devices utilizing engineered interfacial DMI.