Effect of the oxide layer on current-induced spin-orbit torques in Hf vertical bar CoFeB vertical bar MgO and Hf vertical bar CoFeB vertical bar TaOx structures


Akyol M. , Alzate J. G. , Yu G., Upadhyaya P., Wong K. L. , EKİCİBİL A. , et al.

APPLIED PHYSICS LETTERS, cilt.106, 2015 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 106 Konu: 3
  • Basım Tarihi: 2015
  • Doi Numarası: 10.1063/1.4906352
  • Dergi Adı: APPLIED PHYSICS LETTERS

Özet

We study the effect of the oxide layer on the current-induced spin-orbit torques (SOTs) in perpendicularly magnetized Hf|CoFeB|MgO (MgO-capped) or Hf|CoFeB|TaOx (TaOx-capped) structures. The effective fields corresponding to both the field-like and damping-like current-induced SOTs are characterized using electric transport measurements. Both torques are found to be significantly stronger in MgO-capped structures than those in TaOx-capped structures. The difference in field-like and damping-like SOTs in the different structures may be attributed to the different Rashba-like Hamiltonian, arising from the difference in the electric potential profiles across the oxide|ferromagnet interfaces in the two cases, as well as possible structural and oxidation differences in the underlying CoFeB and Hf layers. Our results show that the oxide layer in heavy-metal|ferromagnet|oxide trilayer structures has a very significant effect on the generated SOTs for manipulation of ferromagnetic layers. These findings could potentially be used to engineer SOT devices with enhanced current-induced switching efficiency. (C) 2015 AIP Publishing LLC.