Evidence of Pure Spin-Current Generated by Spin Pumping in Interface-Localized States in Hybrid Metal–Silicon–Metal Vertical Structures

Abstract : Due to the difficulty of growing high-quality semiconductors on ferromagnetic metals, the study of spin diffusion transport in Si was limited to lateral geometry devices. In this work, by using an ultrahigh-vacuum wafer-bonding technique, we have successfully fabricated metal–semiconductor–metal CoFeB/MgO/Si/Pt vertical structures. We hereby demonstrate pure spin-current injection and transport in the perpendicular current flow geometry over a distance larger than 2 μm in n-type Si at room temperature. In those experiments, a pure propagating spin current is generated via ferromagnetic resonance spin pumping and converted into a measurable voltage by using the inverse spin Hall effect occurring in the top Pt layer. A systematic study varying both Si and MgO thicknesses reveals the important role played by the localized states at the MgO–Si interface for the spin-current generation. Proximity effects involving indirect exchange interactions between the ferromagnet and the MgO–Si interface states appears to be a prerequisite to establishing the necessary out-of-equilibrium spin population in Si under the spin-pumping action.
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https://hal-univ-rennes1.archives-ouvertes.fr/hal-01987996
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Submitted on : Monday, January 21, 2019 - 2:37:36 PM
Last modification on : Tuesday, July 23, 2019 - 10:34:11 AM

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Carolina Cerqueira, Jian Yin Qin, Huong Dang, Abdelhak Djeffal, Jean-Christophe Le Breton, et al.. Evidence of Pure Spin-Current Generated by Spin Pumping in Interface-Localized States in Hybrid Metal–Silicon–Metal Vertical Structures. Nano Letters, American Chemical Society, 2019, 19 (1), pp.90-99. ⟨10.1021/acs.nanolett.8b03386⟩. ⟨hal-01987996⟩

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