Giant Tunneling Magnetoresistance in Spin-Filter van der Waals Heterostructures

TL;DR

This paper reports record-high tunneling magnetoresistance in van der Waals heterostructures using atomically thin CrI3 as a spin-filter barrier, enabling multi-bit magnetic memory functionalities at low temperatures.

Contribution

It introduces novel spin-filter magnetic tunnel junctions with CrI3 in van der Waals heterostructures, achieving unprecedented magnetoresistance and multi-resistance states.

Findings

Record 19,000% magnetoresistance at low temperatures.

Multiple resistance states suggest multi-bit memory potential.

CrI3's antiferromagnetic ordering enables high-performance spin filtering.

Abstract

Magnetic multilayer devices that exploit magnetoresistance are the backbone of magnetic sensing and data storage technologies. Here we report novel multiple-spin-filter magnetic tunnel junctions (sf-MTJs) based on van der Waals (vdW) heterostructures in which atomically thin chromium triiodide (CrI3) acts as a spin-filter tunnel barrier sandwiched between graphene contacts. We demonstrate tunneling magnetoresistance which is drastically enhanced with increasing CrI3 layer thickness, reaching a record 19,000% for magnetic multilayer structures using four-layer sf-MTJs at low temperatures. These devices also show multiple resistance states as a function of magnetic field, suggesting the potential for multi-bit functionalities using an individual vdW sf-MTJ. Using magnetic circular dichroism measurements, we attribute these effects to the intrinsic layer-by-layer antiferromagnetic ordering of the atomically thin CrI3. Our work reveals the possibility to push magnetic information storage to the atomically thin limit, and highlights CrI3 as a superlative magnetic tunnel barrier for vdW heterostructure spintronic devices.