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Interfacial spin-orbitronic effects controlled by different oxidation levels at the Co/Al interface

Sachin Krishnia1,*,†, Libor Vojáček2, Tristan da Câmara Santa Clara Gomes1,‡, Nicolas Sebe1, Fatima Ibrahim2, Jing Li3, Luis Moreno Vicente-Arche1, Sophie Collin1, Thibaud Denneulin4 et al.

Rafal E. Dunin-Borkowski4, Sergey A. Nikolaev5, Philippe Ohresser6, Nicolas Jaouen6, André Thiaville7, Albert Fert1, Henri Jaffrès1, Mairbek Chshiev2,8, Nicolas Reyren1, and Vincent Cros1,§

  • *Contact author: sachinbudana@gmail.com
  • †Present address: Institute of Physics, Johannes Gutenberg University Mainz, Staudingerweg 7, 55128 Mainz, Germany.
  • ‡Present address: INESC Microsistemas e Nanotecnologias (INESC MN) Rua Alves Redol 9, 1000-029 Lisbon, Portugal.
  • §Contact author: vincent.cros@cnrs-thales.fr
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Phys. Rev. Applied 24, 024055 – Published 22 August, 2025

DOI: https://doi.org/10.1103/gtwk-mq1y

Abstract

Perpendicular magnetic anisotropy (PMA) and Dzyaloshinskii-Moriya interactions are key interactions in modern spintronics. These interactions are thought to be dominated by the oxidation of the Co/Al interface in the archetypal platinum-cobalt-aluminum oxide system. However, in this study, we observe a double sign change in the anisotropy and about threefold variation in interfacial chiral interaction, influenced not only by the oxidation, but also by the metallic Al thickness. Contrary to previous assumptions about negligible spin-orbit effects at light metal interfaces, we observe not only strong PMA with fully oxidized Al, decreasing and turning negative (in-plane) with less oxygen at the Co/Al interface, but also that the magnetic anisotropy reverts to positive (out-of-plane) values at a fully metallic Co/Al interface. These findings suggest modification in the Co d band via Co/Al orbital hybridization, an effect supported by x-ray absorption spectroscopy and ab initio theory calculations, highlighting the key impact of strain on interfacial mechanisms at a fully metallic Co/Al interface.

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Phys. Rev. Applied 24, 024055– Published 22 August, 2025
  • Received 15 September 2024
  • Revised 14 July 2025
  • Accepted 16 July 2025
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