All-oxide magnetic tunnel junctions with a semiconducting barrier, formed by the half-metallic ferromagnet La0.7Sr0.3MnO3 and n-type semiconductor SrTi0.8Nb0.2O3, were designed, fabricated, and investigated in terms of their magneto-transport properties as a function of applied bias and temperature. We found that the use of the heavily Nb-doped SrTiO3 as a barrier results in significant improvement in the reproducibility of results, i.e., of large tunnel magnetoresistance (TMR) ratios, and a spectral noise density reduced by three orders of magnitude at low temperature. We attribute this finding to a considerably decreased amount of point defects in SrTi0.8Nb0.2O3, especially oxygen vacancies, compared with the conventional insulating SrTiO3 barrier.

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