Boron diffusion induced symmetry reduction and scattering in CoFeB/MgO/CoFeB magnetic tunnel junctions

被引：31

作者：

Bai, Zhaoqiang ^{[1
,2
]}

Shen, Lei ^{[1
]}

Wu, Qingyun ^{[1
]}

Zeng, Minggang ^{[1
]}

Wang, Jian-Sheng ^{[1
]}

Han, Guchang ^{[2
]}

Feng, Yuan Ping ^{[1
]}

机构：

[1] Natl Univ Singapore, Dept Phys, Singapore 117542, Singapore

[2] Agcy Sci Technol & Res, Data Storage Inst, Singapore 117608, Singapore

来源：

PHYSICAL REVIEW B | 2013年 / 87卷 / 01期

关键词：

ROOM-TEMPERATURE; MAGNETORESISTANCE;

D O I：

10.1103/PhysRevB.87.014114

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

By first-principles analysis, we investigate the effect of thermal annealing on structural stability of CoFeB/MgO(thin)/CoFeB magnetic tunnel junctions. The calculated phonon dispersion indicates that Mg3B2O6 (kotoite) is a stable spacer after annealing due to B diffusion into MgO. The calculated tunneling magnetoresistance (TMR) of CoFe/kotoite/CoFe is 210%, which is in good agreement with the available experimental value and 2 orders of magnitude lower than the predicted values of CoFe/MgO/CoFe junctions. The physics of this more realistic TMR value is the change in symmetry from C-4v of MgO to C-2v of kotoite. Such symmetry reduction induces scattering and weakens the tunneling transmission of the Delta(1)-like Bloch states. Our calculations also reveal that the tunneling transmission is sensitive to the electrode/spacer interfacial chemical bonding. Residual boron, localized at the interface due to insufficient annealing temperature, can further reduce the TMR. DOI: 10.1103/PhysRevB.87.014114

引用

页数：6

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