Voltage Control of a van der Waals Spin-Filter Magnetic Tunnel Junction

TL;DR

This paper demonstrates voltage-controlled switching and modulation of tunneling magnetoresistance in a van der Waals magnetic tunnel junction using atomically thin CrI3 and graphene contacts, enabling new spintronic device functionalities.

Contribution

It introduces a dual-gated CrI3-based spin-filter tunnel junction with reversible bistable states and continuous TMR modulation, advancing van der Waals spintronics.

Findings

Reversible switching between magnetic states with large resistance change.

Continuous TMR modulation from 17,000% to 57,000%.

Demonstration of voltage-controlled magnetically moderated transistor action.

Abstract

Atomically thin chromium triiodide (CrI3) has recently been identified as a layered antiferromagnetic insulator, in which adjacent ferromagnetic monolayers are antiferromagnetically coupled. This unusual magnetic structure naturally comprises a series of anti-aligned spin filters which can be utilized to make spin-filter magnetic tunnel junctions with very large tunneling magnetoresistance (TMR). Here we report voltage control of TMR formed by four-layer CrI3 sandwiched by monolayer graphene contacts in a dual-gated structure. By varying the gate voltages at fixed magnetic field, the device can be switched reversibly between bistable magnetic states with the same net magnetization but drastically different resistance (by a factor of ten or more). In addition, without switching the state, the TMR can be continuously modulated between 17,000% and 57,000%, due to the combination of spin-dependent tunnel barrier with changing carrier distributions in the graphene contacts. Our work demonstrates new kinds of magnetically moderated transistor action and opens up possibilities for voltage-controlled van der Waals spintronic devices.