TY - JOUR
T1 - Computer simulation of magnetization flop in magnetic tunnel junctions exchange-biased by synthetic antiferromagnets
AU - Uhm, Y. R.
AU - Lim, S. H.
N1 - Funding Information:
The simulation was performed with a program developed at NIST by Dr. John Oti (now at Euxine Technologies). Financial support from the Tera-level Nanodevices Project (a 21C Frontier Program Funded by the Korean Ministry of Science and Technology) is gratefully acknowledged.
Copyright:
Copyright 2007 Elsevier B.V., All rights reserved.
PY - 2001/12
Y1 - 2001/12
N2 - Computer simulation in a single domain multilayer model is used to investigate magnetization flop in magnetic tunnel junctions, exchange-biased by pinned synthetic antiferromagnets with the multilayer structure NiFe/AlOx/Co/Ru/Co/FeMn. The resistance to magnetization flop increases with decreasing cell size due to increased shape anisotropy and hence increased coercivity of the Co layers in the synthetic antiferromagnet. However, when the synthetic antiferromagnet is not or weakly pinned, the magnetization directions of the two layers sandwiching AlOx, which mainly determine the magnetoresistance, are aligned antiparallel due to a strong magnetostatic interaction, resulting in an abnormal MR change from the high MR state to zero, irrespective of the direction of the free layer switching. This emphasizes an importance of a strong pinning of the synthetic antiferromagnet at small cell dimensions. The threshold field for magnetization flop is found to increase linearly with increasing antiferromagnetic exchange coupling between the two Co layers in the synthetic antiferromagnet. The restoring force from magnetization flop to the normal synthetic antiferromagnetic structure is roughly proportional to the resistance to magnetization flop. Irrespective of the magnetic parameters and cell sizes, the state of magnetization flop does not exist near Ha = 0, indicating that magnetization flop is driven by the Zeeman energy.
AB - Computer simulation in a single domain multilayer model is used to investigate magnetization flop in magnetic tunnel junctions, exchange-biased by pinned synthetic antiferromagnets with the multilayer structure NiFe/AlOx/Co/Ru/Co/FeMn. The resistance to magnetization flop increases with decreasing cell size due to increased shape anisotropy and hence increased coercivity of the Co layers in the synthetic antiferromagnet. However, when the synthetic antiferromagnet is not or weakly pinned, the magnetization directions of the two layers sandwiching AlOx, which mainly determine the magnetoresistance, are aligned antiparallel due to a strong magnetostatic interaction, resulting in an abnormal MR change from the high MR state to zero, irrespective of the direction of the free layer switching. This emphasizes an importance of a strong pinning of the synthetic antiferromagnet at small cell dimensions. The threshold field for magnetization flop is found to increase linearly with increasing antiferromagnetic exchange coupling between the two Co layers in the synthetic antiferromagnet. The restoring force from magnetization flop to the normal synthetic antiferromagnetic structure is roughly proportional to the resistance to magnetization flop. Irrespective of the magnetic parameters and cell sizes, the state of magnetization flop does not exist near Ha = 0, indicating that magnetization flop is driven by the Zeeman energy.
KW - Computer simulation
KW - Magentization flop
KW - Magnetic tunnel junction
KW - Size effects
KW - Synthetic antiferromagnets
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U2 - 10.1016/S0304-8853(01)00256-6
DO - 10.1016/S0304-8853(01)00256-6
M3 - Article
AN - SCOPUS:0035575635
VL - 237
SP - 206
EP - 214
JO - Journal of Magnetism and Magnetic Materials
JF - Journal of Magnetism and Magnetic Materials
SN - 0304-8853
IS - 2
ER -