Study of Magnetization Reversal Process in FeCo/Ru/FeCo Exchange Coupled Synthetic Antiferromagnetic Multilayers

Xi Liu,Hailin Ma,Shunji Ishio

doi:10.1155/2015/452851

Abstract

FeCo/Ru/FeCo exchange coupled synthetic antiferromagnetic multilayers were prepared with two sputtering modes. One is continuous sputtering mode, and the other mode is layer-by-layer sputtering mode. The former mode implies that substrate faced the target and film growth process was continuous when FeCo layers were sputtering, whereas the latter implies that substrate was rotating with the mask at a speed of 5 rpm when FeCo layers were sputtering. It was found that the exchange coupling fieldHexof sample sputtered by layer-by-layer mode was higher than the one sputtered by continuous mode. Domain structures were measured with applying varied in-plane magnetic fields along the easy axis in order to study the magnetization reversal process. We found it is a domain wall move process. When the applied field is smaller thanHex, both the two magnetic layers have domain structure and the domain structure of the two layers is reversed correspondingly. When the applied field is varying in the range of-HextoHex, the domain wall of the two layers moves correspondingly at the same time.

Highlights

Synthetic antiferromagnetic (SAF) multilayer [1] is comprised of two ferromagnetic layers separated by a nonmagnetic metallic spacer layer in which the ferromagnetic layers are coupled through antiferromagnetic interlayer exchange.Such interlayer coupling is subject to the thickness of the nonmagnetic layer [2] and is highly sensitive to structural defects [3]
In an ideal situation with proper thickness of nonmagnetic layer and low structural defects, no remanence can be observed in easy axis and the total magnetization becomes zero when the applied magnetic field is smaller than exchange coupling field Hex
FeCo layer of series B was prepared with a layer-by-layer sputtering mode: substrates and the mask were rotating at the same speed

Summary

Introduction

Synthetic antiferromagnetic (SAF) multilayer [1] is comprised of two ferromagnetic layers separated by a nonmagnetic metallic spacer layer in which the ferromagnetic layers are coupled through antiferromagnetic interlayer exchange Such interlayer coupling is subject to the thickness of the nonmagnetic layer [2] and is highly sensitive to structural defects [3]. SAF multilayers has not been studied yet It is not known if the reversal process is a domain wall move process or moment coherent rotation process. In this present study, FeCo/Ru/FeCo SAF layers were prepared under two different FeCo sputtering modes which significantly changed the surface intermixing, so different exchange coupling fields Hex were measured.

Experiment

Results and Discussions

Conclusion