Instabilities of switching processes in synthetic antiferromagnets

TL;DR

This paper investigates how higher-order anisotropies influence magnetic states and switching behaviors in synthetic antiferromagnets, revealing complex phase diagrams and multidomain patterns that impact MRAM device performance.

Contribution

A phenomenological macrospin model is developed to analyze magnetic states and phase diagrams, highlighting the importance of higher-order anisotropies in synthetic antiferromagnets.

Findings

Existence of out-of-plane magnetization states over broad magnetic field ranges

Formation of symmetric escaped spin-flop phases and multidomain patterns

Switching processes in MRAM deviate from simplified model predictions

Abstract

It is shown that magnetic states and field-driven reorientation transitions in synthetic antiferromagnets crucially depend on contributions of higher-order anisotropies. A phenomenological macrospin model is derived to describe the magnetic states of two antiferromagnetically coupled magnetic thin film elements. The calculated phase diagrams show that magnetic states with out-of-plane magnetization, symmetric escaped spin-flop phases, exist in a broad range of the applied magnetic field. Due to the formation of such states and concomitant multidomain patterns, the switching processes in toggle magnetic random access memory devices (MRAM) can radically deviate from predictions within oversimplified models.