A four-state magnetic tunnel junction switchable with spin-orbit torques

TL;DR

This paper introduces a four-state magnetic tunnel junction controlled by spin-orbit torques, enabling multi-level resistance states for advanced spintronics applications like neuromorphic memory.

Contribution

It demonstrates a novel four-state MTJ with unique resistance states using a TCE structure and spin-orbit torques for field-free switching.

Findings

Four distinct resistance states achieved.

Spin-orbit torques enable field-free switching.

Potential for multi-level spintronic devices.

Abstract

We present a magnetic tunnel junction (MTJ) where its two ferromagnetic layers are in the form of a single ellipse (SE) and two-crossing ellipses (TCE). The MTJ exhibits four distinct resistance states corresponding to the four remanent states of the TCE structure. Flowing current in an underlying Ta layer generates in the adjacent TCE structure spin-orbit torques which induce field-free switching of the four-state MTJ between all its resistance states. The demonstrated four-state MTJ is an important step towards fabricating multi-level MTJs with numerous resistance states which could be important in various spintronics applications, such as multi-level magnetic random access or neuromorphic memory.