Room-Temperature van der Waals Perpendicular Ferromagnet Through Interlayer Magnetic Coupling

Abstract

Ferromagnetic van der Waals (vdW) crystals are promising for future spintronics because they hold huge potential in terms of tunable chemical, mechanical, and physical properties. However, roomtemperature vdW ferromagnets with high-quality perpendicular magnetic anisotropy (PMA) are still elusive, limiting their practical implementations for spintronic applications, such as nonvolatile memories. Here, we show that the magnetic properties of vdW Fe 3 GeTe 2 , including the Curie temperature and the PMA, can be tuned by interlayer exchange coupling (IEC). We demonstrate strong ferromagnetic and antiferromagnetic IECs between sputtered Co and vdW Fe 3 GeTe 2 with Pt and Ru spacer layers, respectively. We find that ferromagnetic IEC enhances the Curie temperature of Fe 3 GeTe 2 while maintaining PMA, which can exhibit 100% out-of-plane remanent magnetization above room temperature. On the other hand, antiferromagnetic coupling weakens the PMA, resulting in a multilevel magnetic hysteresis loop of Fe 3 GeTe 2 even at temperatures as small as 10 K. These interlayered coupled 3D/2D heterostructures could emerge as prime candidates for practical vdW spintronic applications.

Recent advances in two-dimensional intrinsic ferromagnetic materials Fe3X(X=Ge and Ga)Te2 and their heterostructures for spintronics

“…58 The manipulation of the physical properties of Fe 3 GeTe 2 can also be accomplished through the deliberate construction of heterostructures composed of 2D or 3D materials. In 2022, Cao et al 110 reported a modified T c and PMA of Fe 3 GeTe 2 by interlayer exchange coupling, in which the FM or AFM coupling between Fe 3 GeTe 2 and Co layers was achieved by utilizing Pt or Ru space layers, respectively. Interestingly, the T c above room temperature and PMA with 100% remanent magnetization of Fe 3 GeTe 2 could be achieved in Si/SiO 2 /Ta/Pt/Co/Pt/ Fe 3 GeTe 2 with FM coupling for potential practical spintronic application.…”

“…Interestingly, the T c above room temperature and PMA with 100% remanent magnetization of Fe 3 GeTe 2 could be achieved in Si/SiO 2 /Ta/Pt/Co/Pt/ Fe 3 GeTe 2 with FM coupling for potential practical spintronic application. 110 Additionally, more vdWHs composed of 2D materials are woven into the ensuing section. In conclusion, the studies discussed above demonstrate that external stimulations, such as strain, gate voltage, light, hole-doping, environment, substrate, patterning and heterostructure, can effectively modulate the spintronic properties of Fe 3 GeTe 2 .…”

“…Compared with magnetic insulators, 2D CrX 3 (X=Cl, Br and I), magnetic semiconductor 2D Cr 2 X 2 (X=Si and Ge)Te 6 , 2D FM Fe 3 X(X=Ge and Ga)Te 2 are metals with high spin polarization that can be used as excellent electrodes for injecting highly spin-polarized current into 2D magneto-electronic devices. [28][29][30] Furthermore, the large PMA and room-temperature ferromagnetism of Fe 3 X(X=Ge and Ga)Te 2 are suitable for data retention in high-density nonvolatile spintronic devices, 31 while the in-plane magnetic anisotropy of CrTe 2 32 and VSe 2 24 is not conducive to memory devices. Additionally, abundant physical properties, such as the Kondo effect, 33 Nernst effect 34 and itinerant features, 33 are integrated into Fe 3 GeTe 2 , which are rare in other 2D magnets.…”

Automated mechanical exfoliation technique: a spin pumping study in YIG/TMD heterostructures

“…[55][56][57][58][59][60][61][62][63] Hence, the heterostructures comprising the stacking of three-dimensional ferrimagnetic insulator layers and two-dimensional materials stand out as highly promising candidates for feasible devices. 64 It is worth noting that for YIG to exhibit these desirable characteristics, it needs to be carefully grown monocrystalline and in the direction (111). 65 In addition, after preparation, when heated, these characteristics are lost.…”

Spin Valve Effect Based on Out‐Of‐Plane Magnetization Electrodes of Pt/Co/Ru with WSe2 and InSe Barriers

“…[34,35] Among the various kinds of emerging magnetic materials, Fe 3 GeTe 2 (FGT) shows outstanding performances by possessing metallic nature, large PMA, better stability, and relatively high Curie temperature (T c %220 K in bulk and %130 K in monolayer). [36][37][38] Benefiting from the advantages of FGT, the spin valves-based insulator, [35] semi-metal, [34] and semiconductors [14,15,18,39] have been proposed theoretically and verified experimentally. However, there are still some challenges for devices based on FGT, such as the hardness for large-area applications, easy degeneration of ferromagnetic properties in air and T c lower than room temperature, and novel PMA electrodes are strongly desired.…”