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

Guoqiang Yu*, Li Te Chang, Mustafa Akyol, Pramey Upadhyaya, Congli He, Xiang Li, Kin L. Wong, Pedram Khalili Amiri, Kang L. Wang

*Corresponding author for this work

Research output: Contribution to journalArticle

38 Scopus citations

Abstract

We study the current-driven perpendicular magnetization switching in Ta/CoFeB(wedge)/[TaOxor 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 F L) 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 F L. Analysis of the oxidation gradient at the CoFeB/TaOxinterface indicates that the oxidation gradient may play a more important role than the gradient of magnetic anisotropy for the generation of H z F L. For practical applications, the demonstration of perpendicular magnetization switching in Ta/CoFeB(wedge)/MgO/TaOxdevices potentially allows for using MgO-based magnetic tunnel junctions for readout in three-terminal memory devices without the need for external magnetic fields.

Original languageEnglish (US)
Article number102411
JournalApplied Physics Letters
Volume105
Issue number10
DOIs
StatePublished - Sep 8 2014

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)

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