Nearly ideal spin tunneling efficiency in Fe / Mg / MgO / Si O x / n + -Si(001) junctions
2019; American Physical Society; Volume: 3; Issue: 2 Linguagem: Inglês
10.1103/physrevmaterials.3.024411
ISSN2476-0455
AutoresRyosho Nakane, Mitsuki Ichihara, Shōichi Satō, Masaaki Tanaka,
Tópico(s)Quantum and electron transport phenomena
ResumoWe achieved nearly ideal spin tunneling efficiency \ensuremath{\eta} by lowering the interface trap density ${D}_{\mathrm{it}}$ with a $\mathrm{Si}{\mathrm{O}}_{x}$ insertion layer in Fe/Mg/amorphous-MgO(1.0--1.5 nm)/plasma-oxidized $\mathrm{Si}{\mathrm{O}}_{x}(\ensuremath{\sim}0.2\phantom{\rule{0.16em}{0ex}}\mathrm{nm})/{n}^{+}\text{\ensuremath{-}}\mathrm{Si}(001)$ junctions. The spin polarization ${P}_{\mathrm{S}}$ of tunneling electrons was estimated from three-terminal Hanle signals at 4 K. At the optimum MgO thickness and oxidation time, we obtained ${P}_{\mathrm{S}}$ which is nearly equal to the spin polarization ${P}_{\mathrm{FM}}$ of Fe at the Fermi level, that is, $\ensuremath{\eta}={P}_{\mathrm{S}}/{P}_{\mathrm{FM}}=0.93$. By quantitatively estimating ${D}_{\mathrm{it}}$ and ${P}_{\mathrm{S}}$ of various junctions, we show that lowering ${D}_{\mathrm{it}}$ is crucial to obtain \ensuremath{\eta} \ensuremath{\cong} 1.
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