  Electric-field control of spin-dependent properties has become one of the
most attractive phenomena in modern materials research due the promise of new
device functionalities. One of the paradigms in this approach is to
electrically toggle the spin polarization of carriers injected into a
semiconductor using ferroelectric polarization as a control parameter. Using
first-principles density functional calculations, we explore the effect of
ferroelectric polarization of electron-doped BaTiO3 (n-BaTiO3) on the
spin-polarized transmission across the SrRuO3/n-BaTiO3 (001) interface. Our
study reveals that the interface transmission is negatively spin-polarized and
that ferroelectric polarization reversal leads to a change in the transport
spin polarization from -65% to -98%. We show that this effect stems from the
large difference in Fermi wave vectors between up- and down-spins in
ferromagnetic SrRuO3 and a change in the transport regime driven by
ferroelectric polarization switching. The predicted sizeable change in the spin
polarization provides a non-volatile mechanism to electrically control spin
injection in semiconductor-based spintronics devices.
