# Twisted atomic magnetic tunnel junctions with multiple nonvolatile states

## TL;DR

Researchers created magnetic tunnel junctions with multiple nonvolatile states using twisted layers of CrSBr, enabling advanced magnetic memory at the atomic scale.

## Contribution

The novel use of twisted interfaces in 2D antiferromagnets enables multiple nonvolatile states in magnetic tunnel junctions at zero magnetic field.

## Key findings

- Asymmetric MTJs with two nonvolatile states showed up to 700% tunneling magnetoresistance at 2 K.
- Adding a second twisted interface enabled four nonvolatile states switchable via magnetic fields.
- All-antiferromagnetic MTJs with three twisted interfaces demonstrated multiple nonvolatile states.

## Abstract

Magnetic tunnel junctions (MTJs), a key spintronic device, have shown rapid development recently using two-dimensional (2D) magnets. In particular, MTJs formed from twisted 2D antiferromagnets (AFMs) push nonvolatile magnetic information storage to the atomic limit. Here we demonstrate 2D twisted MTJs with multiple distinct nonvolatile states. Asymmetric MTJ structures formed by twisting a single ferromagnetic CrSBr monolayer and a single antiferromagnetic CrSBr bilayer exhibit two distinct states with up to 700% tunneling magnetoresistance in zero magnetic field at 2 K. By adding a second CrSBr monolayer to form a second twisted interface, four nonvolatile states can be accessed in zero magnetic field. More importantly, any one state among the four states can be switched to any other using magnetic fields. We further demonstrate all-antiferromagnetic MTJs with three twisted antiferromagnetic CrSBr bilayers that exhibit multiple nonvolatile states. Our work shows that it is possible to store multiple-state magnetic information in a single device by integrating several twisted interfaces in the atomic limit.

Layered van der Waals magnets like CrSBr, when sandwiched between electrodes form a natural magnetic tunnel junction, albeit lacking the characteristic nonmultiple volatile states at zero field of a magnetic memory. Here, Chen et al overcome this limitation to establish four nonvolatile states at zero field by constructing magnetic tunnel junctions out of twisted monolayers and bilayers of CrSBr with two twisted interfaces.