Layer-Number-Dependent Magnetism and Anomalous Hall Effect in van der Waals Ferromagnet Fe₅GeTe₂

Abstract

Realization of ferromagnetism in the two-dimensional (2D) van der Waals (vdW) crystals opens up a vital route to understand the magnetic ordering in the 2D limit and to design novel spintronics. Here, we report enriched layer-number-dependent magnetotransport properties in the vdW ferromagnet Fe5GeTe2. By studying the magnetoresistance and anomalous Hall effect (AHE) in nanoflakes with thicknesses down to monolayer, we demonstrate that while the bulk crystals exhibit soft ferromagnetism with an in-plane magnetic anisotropy, hard ferromagnetism develops upon thinning, and a perpendicular easy-axis anisotropy is realized in bilayer flakes, which is accompanied by a pronounced enhancement of AHE because of extrinsic mechanisms. For the monolayer flakes, the hard ferromagnetism is replaced by spin-glass-like behavior, in accordance with the localization effect in the 2D limit. Our results highlight the thickness-based tunability of the magnetotransport properties in the atomically thin vdW magnets that promises engineering of high-performance spintronic devices.

Imaging Nucleation and Propagation of Pinned Domains in Few-Layer Fe5–xGeTe2

“…Moreover, due to the limitations of our setup, including an external field limited to OOP and a microwave delivery not optimized for larger than 10 GHz, quantitative imaging is therefore done at near remanence. Few-layer Fe 5 GeTe 2 has a large PMA, resulting in the characteristic M - H loop of a hard magnet, , as illustrated in Figure a. Since the magnetization at remanence ( H = 0 T) is still saturated, we can utilize an AC demagnetization protocol to decouple the field application and NV imaging to estimate H s .…”

Cleavable crystals, crystal structure, and magnetic properties of the NbFe1+xTe3 layered van der Waals telluride

“…Layered vdW tellurides including CrSiTe 3 and CrGeTe 3 , 16–19 Fe 3 AsTe 2 , 20 Fe 3 GeTe 2 , 21,22 Fe 5 AsTe 2 , 23,24 Fe 5 GeTe 2 , 5,15,25–27 and TaFe 1+ x Te 3 28,29 are promising for the design of novel spintronic devices with tailored functionalities. The latter compound is distinguished by the peculiar crystal structure and interesting physical properties.…”

“…11 At the same time, Fe 5 GeTe 2 , which is ferromagnetic below 310 K, 5,[12][13][14] shows the efficient spin filtering within the Fe 5 GeTe 2 /graphene heterostructure already at room temperature. 15 Layered vdW tellurides including CrSiTe 3 and CrGeTe 3 , [16][17][18][19] Fe 3 AsTe 2 , 20 Fe 3 GeTe 2 , 21,22 Fe 5 AsTe 2 , 23,24 Fe 5 GeTe 2 , 5,15,[25][26][27] and TaFe 1+x Te 3 28,29 are promising for the design of novel spintronic devices with tailored functionalities. The latter compound is distinguished by the peculiar crystal structure and interesting physical properties.…”

Nano-Patterned Magnetic Edges in CrGeTe3 for Quasi 1-D Spintronic Devices

“…Some examples include quantum spin chains, − magnetic nanoparticles, and two-dimensional magnetic layers. − These provide promising options for the experimental realization of phenomena, such as quantum criticality and spin frustration, which have been the subject of numerous theoretical predictions. In particular, the intricate evolution of magnetic properties from bulk to thin exfoliated layers ,− offers insights into the physical origin of ferromagnetism (FM) in vdW materials, where anisotropy is thought to be the result of distinct interlayer and intralayer exchange interactions …”

“…Low-dimensional magnetism − and specifically magnetically ordered van der Waals (vdW) materials − have attracted much interest in recent years. The timely and essential progress made now enables the study of unconventional magnetic phenomena with no direct counterpart in bulk 3D materials.…”