High spin polarization and spin signal enhancement in non-local spin valves with Co–Fe alloy injectors and detectors

B. Kaiser, J. Ramberger, J. d. Watts, J. Dewey, C. Leighton

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For applications such as spin accumulation sensors for next-generation hard disk drive read heads, and for fundamental research, it is desirable to increase the spin signal in metallic non-local spin valves, which are central devices in spintronics. To this end, here, we report on the integration of high-spin-polarization Co-Fe binary alloy ferromagnetic injectors and detectors in Al-based non-local spin valves. Room-temperature deposition on amorphous substrates from an alloy target is shown to generate smooth, polycrystalline (110-textured), solid-solution body-centered-cubic Co75Fe25 films, which we characterize by energy dispersive x-ray spectroscopy, x-ray diffraction, x-ray reflectivity, atomic force microscopy, and electronic transport. Simple integration into transparent-interface Al non-local spin valves is then shown to realize up to a factor of ∼5 enhancement of the spin signal relative to Co, with full quantitative analysis yielding strikingly temperature-independent current spin polarizations exceeding 60%. We make a detailed quantitative comparison of these values with prior literature, concluding that Co-Fe alloys present a remarkably facile route to higher spin polarization and spin signals in non-local spin valves, with minimal barrier to adoption.

Original languageEnglish (US)
Article number051108
JournalAPL Materials
Issue number5
StatePublished - May 1 2023

Bibliographical note

Funding Information:
This work was supported by the ASRC (Advanced Storage Research Committee) with additional support from the National Science Foundation through Grant No. DMR-2103711. Parts of this work were conducted in the Minnesota Nano Center, which is supported by the NSF through the National Nanotechnology Coordinated Infrastructure under Grant No. ECCS2025124, and in the UMN Characterization Facility, which is partially supported by the NSF through the MRSEC program. We acknowledge P. Crowell for useful comments and discussions and M. Manno for assistance with EDS analysis.

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© 2023 Author(s).

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