Twisted atomic magnetic tunnel junctions with multiple nonvolatile states

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.