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Abstract Ferromagnetic metal Fe3GeTe2(FGT), whose structure exhibits weak van‐der‐Waals interactions between 5‐atom thick layers, was subjected to liquid‐phase exfoliation (LPE) in N‐methyl pyrrolidone (NMP) to yield a suspension of nanosheets that were separated into several fractions by successive centrifugation at different speeds. Electron microscopy confirmed successful exfoliation of bulk FGT to nanosheets as thin as 6 nm. The ferromagnetic ordering temperature for the nanosheets gradually decreased with the increase in the centrifugation speed used to isolate the 2D material. These nanosheets were resuspended in NMP and treated with an organic acceptor, 7,7,8,8‐tetracyano‐quinodimethane (TCNQ), which led to precipitation of FGT‐TCNQ composite. The formation of the composite material is accompanied by charge transfer from the FGT nanosheets to TCNQ molecules, generating TCNQ⋅−radical anions, as revealed by experimental vibrational spectra and supported by first principles calculations. Remarkably, a substantial increase in magnetic anisotropy was observed, as manifested by the increase in the coercive field from nearly zero in bulk FGT to 1.0 kOe in the exfoliated nanosheets and then to 5.4 kOe in the FGT‐TCNQ composite. The dramatic increase in coercivity of the composite suggests that functionalization with redox‐active molecules provides an appealing pathway to enhancing magnetic properties of 2D materials.
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This content will become publicly available on July 22, 2027
Te Vacancies Induced Magnetic Domains and Domain Wall Stabilization on Fe 3 GeTe 2 Surfaces
ABSTRACT Fe3GeTe2(FGT) is a van der Waals (vdW) ferromagnetic (FM) metal. When the thickness is around tens of nm, it exhibits thickness, temperature, and magnetic field dependent magnetic phases, including skyrmions, magnetic stripes, and labyrinth magnetic domains. These magnetic phases can be further influenced by Fe defects, interfacial Dzyaloshinskii–Moriya interaction (DMI), and strain. Here, the influences of Te vacancies on the magnetic domains on the surfaces of FGT are reported. The Te vacancies are introduced during the exfoliation process and are determined from the atomic resolution scanning tunneling microscopy (STM) images. Te vacancies are found to be responsible for inducing magnetic domains with opposite magnetic moments on the otherwise ferromagnetic surface. Magnetic domain expands upon increasing the temperature, and the Te vacancies serve to stabilize magnetic domain boundaries during the expansion of the magnetic domain sizes. Also, a theoretical model describing the role of Te vacancies to reduce the domain wall energy and hence acting as pinning sites to form the labyrinth like magnetic domain has been presented. The results presented here point out that the Te vacancies may play a significant role in altering magnetic phases.
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- PAR ID:
- 10700568
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Advanced Functional Materials
- ISSN:
- 1616-301X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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