Tunnel spin polarization ofNi80Fe20∕SiO2probed with a magnetic tunnel transistor

Abstract

The tunnel spin polarization of ${\mathrm{Ni}}_{80}{\mathrm{Fe}}_{20}∕{\mathrm{SiO}}_{2}$ interfaces has been investigated using a magnetic tunnel transistor (MTT). The MTT with a ${\mathrm{Ni}}_{80}{\mathrm{Fe}}_{20}∕{\mathrm{SiO}}_{2}$ emitter shows a magnetocurrent of 74% at $100\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, corresponding to a tunnel spin polarization of the ${\mathrm{Ni}}_{80}{\mathrm{Fe}}_{20}∕{\mathrm{SiO}}_{2}$ interface of 27%. This is only slightly lower than the value of 34% for ${\mathrm{Ni}}_{80}{\mathrm{Fe}}_{20}∕{\mathrm{Al}}_{2}{\mathrm{O}}_{3}$ interfaces determined in similar MTT structures. This suggests that ${\mathrm{SiO}}_{2}$ can be applied in semiconductor spintronic devices, for example in $\mathrm{ferromagnet}∕{\mathrm{SiO}}_{2}∕\mathrm{Si}$ tunnel contacts for spin injection.