Memristive switching of MgO based magnetic tunnel junctions

The search for nonvolatile memory concepts has a massive impact on the development of nanoscopic systems with adjustable electrical properties. Capacitor-like structures composed of insulating materials sandwiched between metallic electrodes are envisioned to overcome the limitations associated with conventional charge storage devices and may open the road to neuromorphic computing. Together with phase-change memories [1, 2] two concepts attracted extensive interest [3]: resistive and magnetoresistive random access memories (RAM). In resistive RAM, electrochemical processes within the insulating layer enable the access to multiple resistive states [4, 5, 6, 7]. For magnetic RAM, ferromagnetic electrodes are used to switch the resistance by changing the alignment of the electrodes from parallel to anti-parallel and vice versa [8, 9, 10]. Here we demonstrate that both effects can be observed simultaneously in nano-scale magnetic tunnel junctions (MTJs). The framework of a 2nd order memristive system [11] is utilized to treat the tuning of electrical resistance by concurrent modulation of two material parameters.