  We report on experiments of spin filtering through ultra-thin single-crystal
layers of the insulating and ferromagnetic oxide BiMnO3 (BMO). The spin
polarization of the electrons tunneling from a gold electrode through BMO is
analyzed with a counter-electrode of the half-metallic oxide La2/3Sr1/3MnO3
(LSMO). At 3 K we find a 50% change of the tunnel resistances according to
whether the magnetizations of BMO and LSMO are parallel or opposite. This
effect corresponds to a spin filtering effciency of up to 22%. Our results thus
show the potential of complex ferromagnetic insulating oxides for spin
filtering and injection.
