Tunnel magnetoresistance in nanojunctions based on Sr2FeMoO6

We report on the observation of magnetoresistance in a Sr2FeMoO6 (SFMO)-based tunnel junction. This result is obtained by combining a three-step process for the growth of the Sr2FeMoO6 layer by pulsed laser deposition with a technology allowing the definition of nanometer-sized junctions. A clear positive magnetoresistive signal of 50% is obtained at low temperature in a Sr2FeMoO6/SrTiO3/Co junction. Since the SrTiO3/Co interface is known to have a negative spin polarization of about 20%, this result yields a negative spin polarization of SFMO, which we find to amount to more than 85% in our film. This confirms the half-metallic character of this compound, predicted by band structure calculations.