Effect of MgO Grain Boundaries on the Interfacial Perpendicular Magnetic Anisotropy in Spin-Transfer Torque Magnetic Random Access Memory: A First-Principles Study

Spin-transfer torque magnetic random access memory (STT-MRAM) requires large interfacial perpendicular magnetic anisotropy (iPMA) to be maintained even after many microfabrication steps. The data retention of STT-MRAM depends on the quality of the interface between the ferromagnetic layer and the in...

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Bibliographic Details
Published in:IEEE transactions on magnetics 2023-04, Vol.59 (4), p.1-6
Main Authors: Morishita, Keisuke, Harashima, Yosuke, Araidai, Masaaki, Endoh, Tetsuo, Shiraishi, Kenji
Format: Article
Language:English
Subjects:
Couplings
Density of states
Ferromagnetism
First principles
First-principles calculations
Grain boundaries
Insulation
Iron
Magnesium oxide
Magnetic anisotropy
Magnetic tunneling
Magnetism
Magnetization
Orbitals
Orbits
Perpendicular magnetic anisotropy
Random access memory
spin-transfer torque magnetic random access memory (STT-MRAM)
Torque
Tunnel junctions
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Summary:Spin-transfer torque magnetic random access memory (STT-MRAM) requires large interfacial perpendicular magnetic anisotropy (iPMA) to be maintained even after many microfabrication steps. The data retention of STT-MRAM depends on the quality of the interface between the ferromagnetic layer and the insulating layer in magnetic tunnel junction (MTJ). We have investigated the effects of the grain boundary (GB) in the MgO layer on the iPMA using first-principles calculations. The results show that the iPMA is reduced by the presence of GBs, even though some iPMA remains. This is explained by a decrease in the peak of density of states (DOS) just above the Fermi energy, and that the DOS at high energy is increased in the down spin channel for {d}_{xz} and d_{yz} orbitals. Moreover, we found that the bond structure of Fe-d orbitals around the GB is a key factor controlling the iPMA, in addition to the well-known role of interfacial Fe-O bonds.
ISSN:0018-9464
1941-0069
DOI:10.1109/TMAG.2023.3248488