Spin filtering effect in all-van der Waals heterostructures with WSe2 barriers

Abstract

Exploiting the spin degree of freedom to store and manipulate information provides a paradigm for future microelectronics. The development of van der Waals (vdW) heterostructures has created a fascinating platform for exploring spintronic properties in the two-dimensional (2D) limit. Transition-metal dichalcogenides such as tungsten diselenide (WSe2) have electronic band structures that are ideal for hosting many exotic spin–orbit phenomena. Here, we report the spin-filtering effect in all-vdW heterostructures with WSe2 barrier. Combining 2D-perpendicular magnetic anisotropy Fe3GeTe2 (FGT) with different thicknesses of WSe2, the FGT/WSe2/FGT spin valve shows distinct charge and spin transport behavior. Moreover, the negative magnetoresistance (−4.3%) could be inverted into positive magnetoresistance (up to +25.8%) with decreasing the WSe2 thickness. Furthermore, we proposed a spin-filtering model based on Δ-symmetry electrons tunneling to explain the crossover from negative to positive MR signal through ab initio calculation. These experimental and theoretical results illustrate the rich potential of the families of TMDC materials to control spin currents in 2D spintronic devices.

Room-temperature spin-valve devices based on Fe3GaTe2/MoS2/Fe3GaTe2 2D van der Waals heterojunctions

“…20,21 Under the influence of different thicknesses or defects, the TMDC semiconductors play two different roles in the spin-valve heterojunctions as the conducting or tunneling layer. For example, the spacers in NiFe/MoS 2 /NiFe, 22 NiFe/WSe 2 /NiFe 23 and Fe 3 GeTe 2 /MoS 2 / Fe 3 GeTe 2 24 act as conducting layers, while in the Fe 3 GeTe 2 / WSe 2 /Fe 3 GeTe 2 25 heterojunction, WSe 2 acts as the tunneling layer. Despite these TMDC semiconductors, including MoS 2 , as the spacer layers have been reported, room-temperature all-2D vdW MoS 2 -based spin valves are still rare, making it critical to realize room-temperature FM in 2D vdW materials for the practical application of 2D spin-valve devices in spintronics.…”

Room-Temperature and Tunable Tunneling Magnetoresistance in Fe3GaTe2-Based 2D van der Waals Heterojunctions

“…Comparison of the spin polarization of FM metal/2D vdW heterostructure, FGT-based all-2D vdW heterostructure and Fe 3 GaTe 2 -based all-2D vdW heterostructure from previous reports. ,,,,,− ,,,− …”

“…15−18 2D vdW ferromagnetic crystals with perpendicular magnetic anisotropy (PMA) facilitate the fabrication of all-2D vdW spin valves and MTJs with highquality interfaces due to their easy exfoliation nature and atomically flat surface. For example, MTJs based on Fe 3 GeTe 2 (FGT)/WSe 2 /FGT, 19 FGT/InSe/FGT, 20 preserved at room temperature due to the low Curie temperature of FGT (∼220 K), 17 which greatly hindered the practical application in next-generation spintronic devices. The recent discovery of the above-room-temperature intrinsic ferromagnetic 2D vdW crystal Fe 3 GaTe 2 with a large PMA and high saturation magnetic moment has shed light on the fabrication of room-temperature MTJs for practical use.…”

“…Through the efforts of recent years, experimental results have proved that ferromagnetism can be maintained in 2D systems by magnetic anisotropy, which opens a spin-wave excitation gap that effectively suppresses thermal fluctuations. − 2D vdW ferromagnetic crystals with perpendicular magnetic anisotropy (PMA) facilitate the fabrication of all-2D vdW spin valves and MTJs with high-quality interfaces due to their easy exfoliation nature and atomically flat surface. For example, MTJs based on Fe 3 GeTe 2 (FGT)/WSe 2 /FGT, FGT/InSe/FGT, and FGT/h-BN/FGT heterojunctions demonstrated TMRs of 25.8–300% at low temperatures (10 or 4.2 K), but none of the TMRs were preserved at room temperature due to the low Curie temperature of FGT (∼220 K), which greatly hindered the practical application in next-generation spintronic devices. The recent discovery of the above-room-temperature intrinsic ferromagnetic 2D vdW crystal Fe 3 GaTe 2 with a large PMA and high saturation magnetic moment has shed light on the fabrication of room-temperature MTJs for practical use .…”

Room‐Temperature van der Waals Ferromagnet Switching by Spin‐Orbit Torques

“…The intrinsic above-room-temperature ferromagnetic vdW Fe 3 GaTe 2 is a very competitive ferromagnet due to its robust PMA with Curie temperature T c ≈ 350-380 K, [13] which are critical for the magnetoelectronic devices such as MTJ [21][22][23][24][25] and spin valve. [26][27][28][29][30] Typically, a large tunnel magnetoresistance of 85% at 300 K was recently demonstrated in Fe 3 GaTe 2 /WSe 2 /Fe 3 GaTe 2 MTJs.…”