Influence of topography and Co domain walls on the magnetization reversal of the FeNi layer in FeNi/Al$\_2$O$\_3$/Co magnetic tunnel junctions

TL;DR

This study investigates how substrate topography and domain walls influence magnetization reversal in FeNi/Al₂O₃/Co magnetic tunnel junctions, revealing substrate miscut angle effects and the role of domain wall stray fields.

Contribution

It demonstrates the impact of substrate miscut angle and domain wall stray fields on magnetization reversal mechanisms in magnetic tunnel junctions.

Findings

Larger terraces increase nucleation density and domain wall pinning.

Domain wall stray fields significantly affect the soft magnetic layer.

Reversal mechanisms depend on substrate topography.

Abstract

We have studied the magnetization reversal dynamics of FeNi/Al$\_2$O$\_3$/Co magnetic tunnel junctions deposited on step-bunched Si substrates using magneto-optical Kerr effect and time-resolved x-ray photoelectron emission microscopy combined with x-ray magnetic circular dichroism (XMCD-PEEM). Different reversal mechanisms have been found depending on the substrate miscut angle. Larger terraces (smaller miscut angles) lead to a higher nucleation density and stronger domain wall pinning. The width of domain walls with respect to the size of the terraces seems to play an important role in the reversal. We used the element selectivity of XMCD-PEEM to reveal the strong influence of the stray field of domain walls in the hard magnetic layer on the magnetic switching of the soft magnetic layer.