Multibit Memory Cells Based on Spin-Orbit Torque Driven Magnetization Switching of Nanomagnets with Configurational Anisotropy

Abstract

In this work, we report the fabrication and characterization of novel four and six terminal current-driven magnetic memory cells. In particular, we experimentally demonstrate the magnetization switching of triangular and square magnets through spin-orbit torque by in-plane currents in a Pt/Ni81Fe19 (Py) heterostructure. The spin torques, generated by applying a constant current in one of multiple Pt wires, are used to switch a Py film between its multiple stable magnetic states, as quantified by anisotropic magnetoresistance (AMR) and tunnel magnetoresistance (TMR) measurements at room temperature. The observations have also been confirmed by micromagnetic simulations.

Spin-Orbit Torque Driven Multi-State Device for Memory Applications

“…To overcome this problem, one can alternatively construct a multi-state magnetic cell (e.g., by shape engineering the ferromagnets) to introduce multiple magnetic easy directions (> 2). Recently, such concept has been used to demonstrate four-and six-state spintronic memories that utilized the configurational anisotropy of square and triangular Ni 81 Fe 19 (Py) elements, respectively [3]. Similarly, [4] demonstrated six stable magnetization states in a Py film shaped as three intersecting ellipses.…”