Low current density induced spin-transfer torque switching in CoFeB-MgO magnetic tunnel junctions with perpendicular anisotropy

H. Meng, R. Sbiaa, S. Y H Lua, C. C. Wang, M. A K Akhtar, S. K. Wong, P. Luo, C. J P Carlberg, K. S A Ang

Research output: Contribution to journalArticle

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Abstract

We present the thickness effects of CoFeB free layer on tunnelling magnetoresistive (TMR), perpendicular magnetic anisotropy (PMA) and spin-transfer torque (STT) in CoFeB-MgO based magnetic tunnel junctions (MTJs). It is found that a post-annealing process could significantly improve both TMR and PMA of the MTJ systems. When the free layer thickness is reduced from 1.3 nm to 1 nm, TMR continuously decays from 80% to 20%. On the other hand, PMA is maximized for a 1.28 nm free layer, above which demagnetization becomes stronger and results in lower PMA. If the free layer thickness is very small, dead layer effect could damage interfacial perpendicular anisotropy and PMA is reduced as a consequence. For STT-induced magnetization switching, the lowest intrinsic critical switching current density (Jc0) of 2.1 MA cm-2 is achieved at a free layer thickness of 1.16 nm, accompanied by a TMR of 52% and product of resistance and area (RA) of 16 Ω νm2. Further increasing the free layer thickness will first enhance Jc0 and then reduce it due to the balance between PMA and the total free layer volume. STT studies suggest that the CoFeB free layer thickness should be optimized to make a trade-off among large PMA, high TMR and low switching current density in perpendicular CoFeB-MgO MTJ systems.

Original languageEnglish
Article number405001
JournalJournal of Physics D: Applied Physics
Volume44
Issue number40
DOIs
Publication statusPublished - 2011

Fingerprint

Tunnel junctions
Magnetic anisotropy
low currents
tunnel junctions
torque
Anisotropy
Current density
Torque
current density
anisotropy
Demagnetization
Magnetization
demagnetization
Annealing
damage
magnetization
annealing
decay

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Electronic, Optical and Magnetic Materials
  • Acoustics and Ultrasonics
  • Surfaces, Coatings and Films

Cite this

Low current density induced spin-transfer torque switching in CoFeB-MgO magnetic tunnel junctions with perpendicular anisotropy. / Meng, H.; Sbiaa, R.; Lua, S. Y H; Wang, C. C.; Akhtar, M. A K; Wong, S. K.; Luo, P.; Carlberg, C. J P; Ang, K. S A.

In: Journal of Physics D: Applied Physics, Vol. 44, No. 40, 405001, 2011.

Research output: Contribution to journalArticle

Meng, H. ; Sbiaa, R. ; Lua, S. Y H ; Wang, C. C. ; Akhtar, M. A K ; Wong, S. K. ; Luo, P. ; Carlberg, C. J P ; Ang, K. S A. / Low current density induced spin-transfer torque switching in CoFeB-MgO magnetic tunnel junctions with perpendicular anisotropy. In: Journal of Physics D: Applied Physics. 2011 ; Vol. 44, No. 40.
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