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Electrical spin injection and accumulation at room temperature in an all-metal mesoscopic spin valve

Abstract

Finding a means to generate, control and use spin-polarized currents represents an important challenge for spin-based electronics1,2,3, or ‘spintronics’. Spin currents and the associated phenomenon of spin accumulation can be realized by driving a current from a ferromagnetic electrode into a non-magnetic metal or semiconductor. This was first demonstrated over 15 years ago in a spin injection experiment4 on a single crystal aluminium bar at temperatures below 77 K. Recent experiments5,6,7,8 have demonstrated successful optical detection of spin injection in semiconductors, using either optical injection by circularly polarized light or electrical injection from a magnetic semiconductor. However, it has not been possible to achieve fully electrical spin injection and detection at room temperature. Here we report room-temperature electrical injection and detection of spin currents and observe spin accumulation in an all-metal lateral mesoscopic spin valve, where ferromagnetic electrodes are used to drive a spin-polarized current into crossed copper strips. We anticipate that larger signals should be obtainable by optimizing the choice of materials and device geometry.

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Figure 1: Sample layout.
Figure 2: The spin valve effect at T = 4.2 K (a) and room temperature (b) in the non-local geometry for a sample with 250 nm Py electrode spacing.
Figure 3: Dependence of the magnitude of the spin signal ΔR on the Py electrode distance L.

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Acknowledgements

We thank H. Boeve, J. Das and J. de Boeck at IMEC (Belgium) for support in sample fabrication, M. S. Nijboer for experimental assistance and T. M. Klapwijk for discussions. We wish to thank the Stichting Fundamenteel Onderzoek der Materie and the EU project SPIDER for financial support.

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Jedema, F., Filip, A. & van Wees, B. Electrical spin injection and accumulation at room temperature in an all-metal mesoscopic spin valve. Nature 410, 345–348 (2001). https://doi.org/10.1038/35066533

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