We investigate the possibility of realizing a spintronic memristive device based on the dependence of the tunnel conductance on the relative angle between the magnetization of the two magnetic electrodes in in-plane magnetized tunnel junctions. For this, it is necessary to design a free layer whose magnetization can be stabilized along several or even any in-plane direction between the parallel and the antiparallel magnetic configurations. We experimentally show that this can be achieved by exploiting antiferromagnet-ferromagnet exchange interactions in a regime where the antiferromagnet is thin enough to induce enhanced coercivity and no exchange bias. The frustration of exchange interactions at the interfaces due to competing ferro-and antiferromagnetic interactions is at the origin of an isotropic dissipation mechanism yielding isotropic coercivity. From a modeling point of view, it is shown that this isotropic dissipation can be described by a dry friction term in the Landau-Lifshitz-Gilbert equation. The influence of this dry friction term on the magnetization dynamics of an in-plane magnetized layer submitted to a rotating in-plane field is investigated both analytically and numerically. The possibility to control the free layer magnetization orientation in an in-plane magnetized magnetic tunnel junction by using the spin transfer torque from an additional perpendicular polarizer is also investigated through macrospin simulation. It is shown that the memristor function can be achieved by the injection of current pulses through the stack in the presence of an in-plane static field transverse to the reference layer magnetization, the aim of which is to limit the magnetization rotation between 0° and 180°.

The concept of a spintronic memristor based on angular variation of Tunnel Magnetoresistance relies on the development of an isotropically coercive free layer able to stabilize the magnetization in any in-plane direction. In this work, we first demonstrate those properties in a composite ferromagnet/antiferromagnet/ferromagnet trilayer by performing hysteresis loops at different in-plane angles and rotating field experiments. In the second part, we describe the material composition of the total stack and the fabrication process to create the final device. In the last part, the hysteresis loops at different in-plane angles and the rotating field experiments are performed at device level and compared with the ones performed at full sheet film, confirming the magnetically isotropic nature of the free layer.

In this study, a new type of magnetic memristor is demonstrated. It is based on the variation of the conductivity of a nano-sized magnetic tunnel junction as a function of...