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Effects of transition metal spacers on spin-orbit torques, spin Hall magnetoresistance, and magnetic anisotropy of Pt/Co bilayers

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Author Avci Can Onur, Beach Geoffrey S. D., Gambardella Pietro,
Project Spin-orbitronics in ferromagnets and antiferromagnets
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Original article (peer-reviewed)

Journal Physical Review B
Publisher American Physical Society ({APS})
Volume (Issue) 100(23)
Page(s) 235454 - 235454
ISBN 2469-9950
Title of proceedings Physical Review B
DOI 10.1103/physrevb.100.235454

Open Access

URL https://arxiv.org/abs/2002.02162
Type of Open Access Repository (Green Open Access)

Abstract

We studied the effect of inserting 0.5-nm-thick spacer layers (Ti, V, Cr, Mo, W) at the Pt/Co interface on the spin-orbit torques, the Hall effect, magnetoresistance, saturation magnetization, and magnetic anisotropy. We find that the dampinglike spin-orbit torque decreases substantially for all samples with a spacer layer compared to the reference Pt/Co bilayer, consistently with the opposite sign of the atomic spin-orbit coupling constant of the spacer elements relative to Pt. The reduction of the dampinglike torque is monotonic with atomic number for the isoelectronic 3d, 4d, and 5d elements, with the exception of V that has a stronger effect than Cr. The fieldlike spin-orbit torque almost vanishes for all spacer layers irrespective of their composition, suggesting that this torque predominantly originates at the Pt/Co interface. The anomalous Hall effect, magnetoresistance, and saturation magnetization are also all reduced substantially, whereas the sheet resistance is increased in the presence of the spacer layer. Finally, we evidence a correlation between the amplitude of the spin-orbit torques, the spin-Hall-like magnetoresistance, and the perpendicular magnetic anisotropy. These results highlight the significant influence of ultrathin spacer layers on the magnetotransport properties of heavy-metal/ferromagnetic systems.
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