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Abstract Spin–orbit torques generated by a spin current are key to magnetic switching in spintronic applications. The polarization of the spin current dictates the direction of switching required for energy‐efficient devices. Conventionally, the polarizations of these spin currents are restricted to be along a certain direction due to the symmetry of the material allowing only for efficient in‐plane magnetic switching. Unconventional spin–orbit torques arising from novel spin current polarizations, however, have the potential to switch other magnetization orientations such as perpendicular magnetic anisotropy, which is desired for higher density spintronic‐based memory devices. Here, it is demonstrated that low crystalline symmetry is not required for unconventional spin–orbit torques and can be generated in a nonmagnetic high symmetry material, iridium dioxide (IrO2), using epitaxial design. It is shown that by reducing the relative crystalline symmetry with respect to the growth direction large unconventional spin currents can be generated and hence spin–orbit torques. Furthermore, the spin polarizations detected in (001), (110), and (111) oriented IrO2thin films are compared to show which crystal symmetries restrict unconventional spin transport. Understanding and tuning unconventional spin transport generation in high symmetry materials can provide a new route towards energy‐efficient magnetic switching in spintronic devices.
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Crystallographic Spin Torque Conductivity Tensor of Epitaxial IrO 2 Thin Films for Oxide Spintronics
Abstract Unconventional spin‐orbit torques arising from electric‐field‐generated spin currents in anisotropic materials have promising potential for spintronic applications, including for perpendicular magnetic switching in high‐density memory applications. Here, all the independent elements of the spin torque conductivity tensor allowed by bulk crystal symmetries for the tetragonal conductor IrO2are determined via measurements of conventional (in‐plane) anti‐damping torques for IrO2thin films in the high‐symmetry (001) and (100) orientations. It is then tested whether rotational transformations of this same tensor can predict both the conventional and unconventional anti‐damping torques for IrO2thin films in the lower‐symmetry (101), (110), and (111) orientations, finding good agreement. The results confirm that spin‐orbit torques from all these orientations are consistent with the bulk symmetries of IrO2, and show how simple measurements of conventional torques from high‐symmetry orientations of anisotropic thin films can provide an accurate prediction of the unconventional torques from lower‐symmetry orientations.
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- PAR ID:
- 10579691
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Advanced Materials
- Volume:
- 37
- Issue:
- 9
- ISSN:
- 0935-9648
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1002/adma.202414267
