Classification of hysteresis loops for exchange biased F/NM/F trilayer with antiferromagnetic interlayer coupling

Abstract

Major hysteresis loops of the F/NM/F/AF structure are classified according to the magnetization process, with the assumption of coherent rotation for each F component and antiferromagnetic coupling between the two F layers. Magnetic stable states of the system as well as specific reversal modes of magnetization during each stage of the major hysteresis cycle are studied in detail based on energetics analysis, in the whole range of exchange bias field and interlayer antiferromagnetic coupling strength. The analysis shows 12 different types of major hysteresis loops for this system and is confirmed by simulation. Strategies to determine key material parameters for the F/NM/F/AF structure from major hysteresis loops are proposed and illustrated by numerical simulation. The research shows a subtle tuning of the magnetization process in the F/NM/F/AF structure, collectively by exchange biasing and interlayer antiferromagnetic coupling. Practically, this serves as a theoretical grounding for the identification of root causes of failure in the product analysis of GMR (giant magnetoresistance) sensors.