Unconventional Hall effect and its variation with Co-doping in van der Waals Fe3GeTe2

Abstract

Two-dimensional (2D) van der Waals (vdW) magnetic materials have attracted a lot of attention owing to the stabilization of long range magnetic order down to atomic dimensions, and the prospect of novel spintronic devices with unique functionalities. The clarification of the magnetoresistive properties and its correlation to the underlying magnetic configurations is essential for 2D vdW-based spintronic devices. Here, the effect of Co-doping on the magnetic and magnetotransport properties of Fe3GeTe2 have been investigated. Magnetotransport measurements reveal an unusual Hall effect behavior whose strength was considerably modified by Co-doping and attributed to arise from the underlying complicated spin textures. The present results provide a clue to tailoring of the underlying interactions necessary for the realization of a variety of unconventional spin textures for 2D vdW FM-based spintronics.

Effects of Fe Deficiency and Co Substitution in Polycrystalline and Single Crystals of Fe3GeTe2

“…The presence of a topological Hall effect has recently been observed in Fe 3 GeTe 2 ; this signal is frequently taken as the hallmark of skyrmions. 24,33 Since Fe 3 GeTe 2 crystallizes in the centrosymmetric hexagonal space group P6 3 /mmc (No. 194) as shown in Figure 1, the mechanism for the stabilization of skyrmions in bulk Fe 3 GeTe 2 is currently unclear.…”

Giant coercivity enhancement in a room-temperature van der Waals magnet through substitutional metal-doping

“…In particular, in metallic ferromagnetic (FM) materials, substitutional doping not only alters the intrinsic magnetic properties, such as saturation magnetization (M s ), anisotropy field (H k ), and Curie temperature (T C ), but may also affect micro-magnetic characteristics, such as domain motion and domain wall energy. [1][2][3][4][5][6][7] For this reason, the effect of substitutional doping on vdW magnets cannot be understood in a simple way, but various aspects should be considered to precisely analyze the outcome. Substitutional doping of Fe x GeTe 2 (x = 3, 4, and 5), which are metallic FM materials, has been intensively researched because of their comparatively high T C (Fe 3 GeTe 2 ∼ 220 K, Fe 4 GeTe 2 ∼ 280 K, Fe 5 GeTe 2 ∼ 300 K) and tunable material properties.…”

“…Substitutional doping of Fe x GeTe 2 (x = 3, 4, and 5), which are metallic FM materials, has been intensively researched because of their comparatively high T C (Fe 3 GeTe 2 ∼ 220 K, Fe 4 GeTe 2 ∼ 280 K, Fe 5 GeTe 2 ∼ 300 K) and tunable material properties. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] Their magnetic properties are shown to be modulated with substitutional doping, when the Fe atom is replaced with other transition metals such as Co and Ni. 2,[4][5][6][7] In the case of (Fe 1−x Co x ) 3 GeTe 2 , substitutional doping detrimentally affects the T C of crystals.…”

Spin-polarized supercurrent through the van der Waals Kondo lattice ferromagnet Fe$_3$GeTe$_2$

“…High quality single crystals of Fe 3 GeTe 2 were synthesized by chemical vapor transport. The details of the growth parameters and the characterization are reported elsewhere [38]. Owing to the van der Waals bonding between the different layers, the single crystals were cleavable by mechanical exfoliation.…”

“…Magnetization measurements revealed a critical temperature of ∼ 206 K [38]. In order to investigate the local magnetic properties, we imaged the ferromagnetic domains of Fe 3 GeTe 2 directly by low-temperature magnetic force microscopy.…”