Large spin-accumulation signal in Si for epitaxial CoFe/highly (100)-textured MgO/Si devices

•Mg insertion between MgO and Si leads to highly (100)-textured MgO.•CoFe epitaxially grows on the highly textured MgO.•The devices with highly textured MgO and with polycrystalline MgO are evaluated.•The magnitude of spin-accumulation in Si depends on the texture of MgO.•The CoFe/MgO/Mg/Si devices show larger spin-accumulation in the low-RA region.

Spin-accumulation in Si for epitaxial CoFe/highly (100)-textured MgO/Si devices is investigated and compared to that for CoFe/polycrystalline or (110)-textured MgO/Si devices. We find that magnesium (Mg) insertion between MgO and Si leads to highly (100)-textured MgO and epitaxial CoFe films. Interface resistance dependence on magnitude of spin-accumulation signal by the three-terminal Hanle measurement is quantitatively evaluated. Devices with highly (100)-textured MgO show larger magnitude of spin-accumulation signal in the low-interface-resistance region, than that with polycrystalline or (110)-textured MgO. These results indicate that magnitude of spin-accumulation signal depends on the crystallinity or the texture of ferromagnet/tunnel barrier layers on Si.