Spin-Dependent Transport in van der Waals Magnetic Tunnel Junctions with Fe₃GeTe₂ Electrodes

Abstract

Van der Waals (vdW) heterostructures, stacking different two-dimensional materials, have opened up unprecedented opportunities to explore new physics and device concepts. Especially interesting are recently discovered two-dimensional magnetic vdW materials, providing new paradigms for spintronic applications. Here, using density functional theory (DFT) calculations, we investigate the spin-dependent electronic transport across vdW magnetic tunnel junctions (MTJs) composed of Fe3GeTe2 ferromagnetic electrodes and a graphene or hexagonal boron nitride (h-BN) spacer layer. For both types of junctions, we find that the junction resistance changes by thousands of percent when the magnetization of the electrodes is switched from parallel to antiparallel. Such a giant tunneling magnetoresistance (TMR) effect is driven by dissimilar electronic structure of the two spin-conducting channels in Fe3GeTe2, resulting in a mismatch between the incoming and outgoing Bloch states in the electrodes and thus suppressed transmission for an

Ultrathin Scattering Spin Filter and Magnetic Tunnel Junction Implemented by Ferromagnetic 2D van der Waals Material

“…It is worth noting that our value is closer to the experimental value31 than ref. 40 Here, the two‐probe model for mesoscopic electronic scattering is closer to the experimental setup, and thus we infer that our simulation could give reliable results in accordance with the actual situation. By contrast, the TMR of single‐layer FGT‐hBN‐FGT heterostructure is comparable with that of bulk FGT.…”

“…Recently, a behavior of the tunneling resistance31 and large anomalous Hall effect30 were observed in bulk FGT/hBN/FGT heterostructures. A theoretical analysis for the mechanism was then proposed40 and a very large magnetoresistance was reported. By the doping of ionic gate, the Curie temperature of atomically thin FGT is dramatically elevated to room temperature 30.…”

Large Tunneling Magnetoresistance in van der Waals Ferromagnet/Semiconductor Heterojunctions

“…[ 27 ] The FGT‐based spin valves with a semiconductor or an insulator as the spacer layer, or even a ferroelectric layer have been proposed theoretically. [ 28–30 ] Experimentally, the tunneling FGT/hBN/FGT spin valves have been demonstrated and a high MR of 160% was achieved. [ 31 ] The semiconductor MoS 2 has also been used as the spacer layer in FGT/MoS 2 /FGT devices, but the MoS 2 acts as a conductive layer rather than a tunneling barrier.…”

Two-dimensional van der Waals spinterfaces and magnetic-interfaces

“…For example, 2D materials with different crystal structures and lattice constants can be stacked into heterostructures, without the structural and electronic detrimental effect seen in conventional epitaxial thin films 104,105 . Since the interlayer interaction is of the van der Waals kind, the 2D materials forming FM/Insulator/FM device 106,107 architectures can stay electronically decoupled, circumventing complex covalent hybridization at interfaces and interface states issues with traditional evaporated metaloxide interfaces 2,3,103 . This implies that van der Waal's magnetic layers introduce new concepts of spin filtering beyond the usual spin injection/detection schemes while exploiting only the change of magnetic ordering into the lamellar structure [108][109][110] .…”