Thickness effect on the easy axis distribution in exchange biased Co/IrMn bilayers

H. S. Tarazona; M. Tafur; Justiniano Quispe Marcatoma; Carlos Vladimir Landauro Saenz; E. Baggio-Saitovitch; D. S. Schmool

doi:10.1016/j.physb.2019.05.005

Thickness effect on the easy axis distribution in exchange biased Co/IrMn bilayers

H. S. Tarazona, M. Tafur, Justiniano Quispe Marcatoma, Carlos Vladimir Landauro Saenz, E. Baggio-Saitovitch, D. S. Schmool

Research output: Contribution to journal › Article › peer-review

1 Scopus citations

Abstract

It is commonly assumed that in uncompensated FM/AF interfaces, the easy axes of antiferromagnetic grains are aligned toward the magnetic field direction applied during the film growth. However, due to several intrinsic and extrinsic factors, these easy axes can be aligned away from the unidirectional axis. In this context, the aim of this work is to study the relationship between the easy axes distribution (EAD) and thickness of both the ferromagnetic (FM) and antiferromagnetic (AF) layers in Co/IrMn bilayer systems. A phenomenological model for the free energy of the system that takes into account a domain wall formation in the AF layer and a Gaussian-type distribution of their easy axes is used. Thus, we simulate and fit the magnetization curves and get several magnetic parameters like rotatable anisotropy field, exchange bias field, coercivity and magnetic anisotropy. Our results show that when the AF thickness is increased, the width of the easy-axis distribution also increases following a power-law relationship. However, no correlation is observed when the FM thickness is varied. Furthermore, considering an easy-axis distribution we observe a significant reduction in coercivity as well as a slight decrease of the exchange bias field.

Original language	English
Pages (from-to)	11-16
Number of pages	6
Journal	Physica B: Condensed Matter
Volume	567
DOIs	https://doi.org/10.1016/j.physb.2019.05.005
State	Published - 15 Aug 2019
Externally published	Yes

Bibliographical note

Funding Information:
This work has been partially supported by the Brazilian agencies CNPq and FAPERJ . H. S. T. thanks to the Peruvian Doctoral Scholarship Program of CIENCIACTIVA (CONCYTEC) for financial support under Grand #218-2014-FONDECYT . J. Q-M and C. V. L. are grateful to CIENCIACTIVA (CONCYTEC) for partial financial support through the Excellence Center Programs. J. Q-M is also grateful to the GEMaC Laboratory, for the hospitality during the preparation of this manuscript. In addition, E. B. S. acknowledges support from FAPERJ through several grants including Emeritus Professor fellow and CNPq for BPA and corresponding grants.

Keywords

Easy axis distribution
Exchange bias
Rotatable anisotropy

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title = "Thickness effect on the easy axis distribution in exchange biased Co/IrMn bilayers",

abstract = "It is commonly assumed that in uncompensated FM/AF interfaces, the easy axes of antiferromagnetic grains are aligned toward the magnetic field direction applied during the film growth. However, due to several intrinsic and extrinsic factors, these easy axes can be aligned away from the unidirectional axis. In this context, the aim of this work is to study the relationship between the easy axes distribution (EAD) and thickness of both the ferromagnetic (FM) and antiferromagnetic (AF) layers in Co/IrMn bilayer systems. A phenomenological model for the free energy of the system that takes into account a domain wall formation in the AF layer and a Gaussian-type distribution of their easy axes is used. Thus, we simulate and fit the magnetization curves and get several magnetic parameters like rotatable anisotropy field, exchange bias field, coercivity and magnetic anisotropy. Our results show that when the AF thickness is increased, the width of the easy-axis distribution also increases following a power-law relationship. However, no correlation is observed when the FM thickness is varied. Furthermore, considering an easy-axis distribution we observe a significant reduction in coercivity as well as a slight decrease of the exchange bias field.",

keywords = "Easy axis distribution, Exchange bias, Rotatable anisotropy",

author = "Tarazona, {H. S.} and M. Tafur and {Quispe Marcatoma}, Justiniano and {Landauro Saenz}, {Carlos Vladimir} and E. Baggio-Saitovitch and Schmool, {D. S.}",

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AU - Tarazona, H. S.

AU - Tafur, M.

AU - Quispe Marcatoma, Justiniano

AU - Landauro Saenz, Carlos Vladimir

AU - Baggio-Saitovitch, E.

AU - Schmool, D. S.

PY - 2019/8/15

Y1 - 2019/8/15

N2 - It is commonly assumed that in uncompensated FM/AF interfaces, the easy axes of antiferromagnetic grains are aligned toward the magnetic field direction applied during the film growth. However, due to several intrinsic and extrinsic factors, these easy axes can be aligned away from the unidirectional axis. In this context, the aim of this work is to study the relationship between the easy axes distribution (EAD) and thickness of both the ferromagnetic (FM) and antiferromagnetic (AF) layers in Co/IrMn bilayer systems. A phenomenological model for the free energy of the system that takes into account a domain wall formation in the AF layer and a Gaussian-type distribution of their easy axes is used. Thus, we simulate and fit the magnetization curves and get several magnetic parameters like rotatable anisotropy field, exchange bias field, coercivity and magnetic anisotropy. Our results show that when the AF thickness is increased, the width of the easy-axis distribution also increases following a power-law relationship. However, no correlation is observed when the FM thickness is varied. Furthermore, considering an easy-axis distribution we observe a significant reduction in coercivity as well as a slight decrease of the exchange bias field.

AB - It is commonly assumed that in uncompensated FM/AF interfaces, the easy axes of antiferromagnetic grains are aligned toward the magnetic field direction applied during the film growth. However, due to several intrinsic and extrinsic factors, these easy axes can be aligned away from the unidirectional axis. In this context, the aim of this work is to study the relationship between the easy axes distribution (EAD) and thickness of both the ferromagnetic (FM) and antiferromagnetic (AF) layers in Co/IrMn bilayer systems. A phenomenological model for the free energy of the system that takes into account a domain wall formation in the AF layer and a Gaussian-type distribution of their easy axes is used. Thus, we simulate and fit the magnetization curves and get several magnetic parameters like rotatable anisotropy field, exchange bias field, coercivity and magnetic anisotropy. Our results show that when the AF thickness is increased, the width of the easy-axis distribution also increases following a power-law relationship. However, no correlation is observed when the FM thickness is varied. Furthermore, considering an easy-axis distribution we observe a significant reduction in coercivity as well as a slight decrease of the exchange bias field.

KW - Easy axis distribution

KW - Exchange bias

KW - Rotatable anisotropy

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JO - Physica B: Condensed Matter

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Thickness effect on the easy axis distribution in exchange biased Co/IrMn bilayers

Abstract

Bibliographical note

Keywords

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