Spin–orbit torque engineering in β-W/CoFeB heterostructures with W–Ta or W–V alloy layers between β-W and CoFeB

Gyu Won Kim, Do Duc Cuong, Yong Jin Kim, In Ho Cha, Taehyun Kim, Min Hyeok Lee, Ouk Jae Lee, Hionsuck Baik, Soon Cheol Hong, Sonny H. Rhim, Young Keun Kim

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

Abstract

The spin–orbit torque (SOT) resulting from a spin current generated in a nonmagnetic transition metal layer offers a promising magnetization switching mechanism for spintronic devices. To fully exploit this mechanism, in practice, materials with high SOT efficiencies are indispensable. Moreover, new materials need to be compatible with semiconductor processing. This study introduces W–Ta and W–V alloy layers between nonmagnetic β-W and ferromagnetic CoFeB layers in β-W/CoFeB/MgO/Ta heterostructures. We carry out first-principles band structure calculations for W–Ta and W–V alloy structures to estimate the spin Hall conductivity. While the predicted spin Hall conductivity values of W–Ta alloys decrease monotonically from −0.82 × 103 S/cm for W100 at% as the Ta concentration increases, those of W–V alloys increase to −1.98 × 103 S/cm for W75V25 at% and then gradually decrease. Subsequently, we measure the spin Hall conductivities of both alloys. Experimentally, when β-W is alloyed with 20 at% V, the absolute value of the spin Hall conductivity considerably increases by 36% compared to that of the pristine β-W. We confirm that the W–V alloy also improves the SOT switching efficiency by approximately 40% compared to that of pristine β-W. This study demonstrates a new material that can act as a spin current-generating layer, leading to energy-efficient spintronic devices.

Original languageEnglish
Article number60
JournalNPG Asia Materials
Volume13
Issue number1
DOIs
Publication statusPublished - 2021 Dec

ASJC Scopus subject areas

  • Modelling and Simulation
  • Materials Science(all)
  • Condensed Matter Physics

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