Self-Modulated Magnetism in Two-Dimensional Ferromagnet Fe3GeTe2 Induced by Ambient Effects.

In the vast family of two-dimensional (2D) van der Waals materials, 2D magnets have unique advantages in the experimental realization of numerous theoretical works and fundamental exploration of high-performance spintronic devices in the 2D limit. Fe₃GeTe₂ (FGT), as a typical 2D metallic ferromagnet, is a promising candidate to achieve functional devices at room temperature due to its relatively high Curie temperature (T_C) and strong perpendicular magnetic anisotropy (PMA). Here, we investigated self-modulated magnetic properties of FGT nanoflakes in an ambient environment by anomalous Hall effect (AHE). Unique double square-shaped hysteresis loops are observed in oxidized Fe₃GeTe₂ nanoflakes induced by ambient effects. We propose a phenomenological model based on antiferromagnetic/ferromagnetic coupling in the FGT nanoflakes with oxidized surface layers to elucidate this observation. Compared with a single square-shaped hysteresis loop of well-preserved FGT, double square-shaped hysteresis loops exhibit four-resistance plateaus, which can be regarded as a kind of media for information storage or sensing, showing potential applications in next-generation spintronic devices. [ABSTRACT FROM AUTHOR]