Magnetization reversal and field annealing effects in perpendicular exchange-biased Co/Pt multilayers and spin valves with perpendicular magnetization

Sebastiaan van Dijken*, Matthew Crofton, M. Czapkiewicz, M. Zoladz, T. Stobiecki

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

33 Citations (Scopus)

Abstract

A study on the Co layer thickness dependence of the magnetization reversal process and magnetoresistance of perpendicular exchange-biased CoPt multilayers and spin valves with perpendicular magnetization is presented. The hysteresis of [20 Å Ptt Å Co]3 100 Å IrMn20 Å Pt multilayers with t5 Å are found to be asymmetric after deposition. This asymmetry reflects a lateral variation in the perpendicular exchange-bias direction due to the growth of IrMn onto multidomain CoPt multilayers. Magnetic annealing in a perpendicular field removes the switching asymmetry and leads to a maximum exchange-bias field of 16.3 mT for t=7 Å. Perpendicular spin valves with an optimized structure of 50 Ta20 Å Ptt Å Co30 Å Cut Å Co20 Å Pt6 Å Co3 Å Pt100 IrMn20 Å Pt are found to exhibit good switching behavior but limited magnetoresistance for small Co layer thickness. The magnetoresistance of these spin valves increases with t up to a maximum of 3.9% for t=10 Å, beyond which it decreases due to simultaneous magnetization reversal in the ferromagnetic layers. Magnetic field annealing of these top-pinned structures reduces the exchange-bias field and the magnetoresistance.

Original languageEnglish
Article number083901
Number of pages7
JournalJournal of Applied Physics
Volume99
Issue number8
DOIs
Publication statusPublished - 2006
MoE publication typeA1 Journal article-refereed

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