Giant tunneling magnetoresistance in spin-filter van der Waals heterostructures

Abstract

Magnetic multilayer devices that exploit magnetoresistance are the backbone of magnetic sensing and data storage technologies. Here, we report multiple-spin-filter magnetic tunnel junctions (sf-MTJs) based on van der Waals (vdW) heterostructures in which atomically thin chromium triiodide (CrI) acts as a spin-filter tunnel barrier sandwiched between graphene contacts. We demonstrate tunneling magnetoresistance that is drastically enhanced with increasing CrI layer thickness, reaching a record 19,000% for magnetic multilayer structures using four-layer sf-MTJs at low temperatures. Using magnetic circular dichroism measurements, we attribute these effects to the intrinsic layer-by-layer antiferromagnetic ordering of the atomically thin CrI Our work reveals the possibility to push magnetic information storage to the atomically thin limit and highlights CrI as a superlative magnetic tunnel barrier for vdW heterostructure spintronic devices.

Van der Waals magnets: Wonder building blocks for two‐dimensional spintronics?

“…In fact, “vdW‐MTJs” have been successfully fabricated, an example of which is based on a graphite/CrI 3 /graphite sandwich structure that possesses a large tunneling magnetoresistance . Figure A shows a schematic of such vdW‐MTJ with bilayer CrI 3 functioning as a spin‐filter . The magnetic‐field‐dependent tunneling current at a selected bias voltage and RMCD signal are shown in Figure B, from which a double spin filter effect is evident: in the antiparallel spin states at low field, the current is small because of suppressed spin‐conserving tunneling of an electron through the adjacent layers .…”

“…Heterostructures and devices based on 2D‐vdW magnets are expected to possess a great variety of properties with strong application potential. Notable examples include the giant magnetoresistance and spin‐filtering phenomena in 2D spin‐valves and tunnel junctions …”

2D Atomic Crystals: A Promising Solution for Next‐Generation Data Storage

“…Pleasantly, spinfilter MTJs (sf-MTJs) based on different layers of CrI 3 with giant TMR were demonstrated by Song et al [81] Thin graphene flakes were placed on the top and bottom of CrI 3 , and the structure contains h-BN flakes to avoid the degradation (Figure 14a). Pleasantly, spinfilter MTJs (sf-MTJs) based on different layers of CrI 3 with giant TMR were demonstrated by Song et al [81] Thin graphene flakes were placed on the top and bottom of CrI 3 , and the structure contains h-BN flakes to avoid the degradation (Figure 14a).…”

“…They adopted scalable techniques, which did not require the transfer of h-BN flakes. [81] Copyright 2016, AAAS. The CVD-grown h-BN possessed many grain boundaries (GBs) that provided thin defective paths for the formation of filaments and the GBs per cell are controllable by tuning CVD growth parameter.…”

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

“…According to the Mermin–Wagner theorem,18 2D long‐range FM order cannot exist in an isotropic magnetic system. Recently, people found that 2D layered CrI 3 ,19–27 Cr 2 Ge 2 Te 6 ,28 and CrSiTe 3 29 possesses intrinsic magnetocrystalline anisotropy against thermal fluctuations. However, the Curie temperatures of CrI 3 , Cr 2 Ge 2 Te 6 , and CrSiTe 3 are only dozens of Kelvins.…”