Current-driven perpendicular magnetization switching in Ta/CoFeB/[TaOx or MgO/TaOx] films with lateral structural asymmetry


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Yu G., Chang L., Akyol M. , Upadhyaya P., He C., Li X., ...Daha Fazla

APPLIED PHYSICS LETTERS, cilt.105, sa.10, 2014 (SCI İndekslerine Giren Dergi) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 105 Konu: 10
  • Basım Tarihi: 2014
  • Doi Numarası: 10.1063/1.4895735
  • Dergi Adı: APPLIED PHYSICS LETTERS

Özet

We study the current-driven perpendicular magnetization switching in Ta/CoFeB(wedge)/[TaOx or MgO/TaOx] devices with a lateral structural asymmetry introduced by a varying CoFeB thickness. In these devices, an in-plane current can generate a field-like torque and its corresponding effective magnetic field (H-z(FL)) is out-of-plane, which can deterministically switch perpendicular magnetization at zero magnetic field. Experimental results indicate that the method used for breaking lateral structural symmetry greatly affects the resulting field-like torque, and that the gradient of perpendicular anisotropy, resulting from the CoFeB thickness variation, is not by itself sufficient to give rise to the current-induced H-z(FL). Analysis of the oxidation gradient at the CoFeB/TaOx interface indicates that the oxidation gradient may play a more important role than the gradient of magnetic anisotropy for the generation of H-z(FL). For practical applications, the demonstration of perpendicular magnetization switching in Ta/CoFeB(wedge)/MgO/TaOx devices potentially allows for using MgO-based magnetic tunnel junctions for readout in three-terminal memory devices without the need for external magnetic fields. (C) 2014 AIP Publishing LLC.