Abstract
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.
| Original language | English |
|---|---|
| Pages (from-to) | 206-214 |
| Number of pages | 9 |
| Journal | Journal of Magnetism and Magnetic Materials |
| Volume | 237 |
| Issue number | 2 |
| DOIs | |
| Publication status | Published - 2001 Dec 1 |
| Externally published | Yes |
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Keywords
- Computer simulation
- Magentization flop
- Magnetic tunnel junction
- Size effects
- Synthetic antiferromagnets
ASJC Scopus subject areas
- Condensed Matter Physics
Cite this
Computer simulation of magnetization flop in magnetic tunnel junctions exchange-biased by synthetic antiferromagnets. / Uhm, Y. R.; Lim, Sang Ho.
In: Journal of Magnetism and Magnetic Materials, Vol. 237, No. 2, 01.12.2001, p. 206-214.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Computer simulation of magnetization flop in magnetic tunnel junctions exchange-biased by synthetic antiferromagnets
AU - Uhm, Y. R.
AU - Lim, Sang Ho
PY - 2001/12/1
Y1 - 2001/12/1
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
UR - http://www.scopus.com/inward/record.url?scp=0035575635&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0035575635&partnerID=8YFLogxK
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 -