Low noise all-oxide magnetic tunnel junctions based on a La$_{0.7}$Sr$_{0.3}$Mn$_{O3}$/Nb:SrTiO$_3$ interface
Résumé
All-oxide magnetic tunnel junctions with a semiconducting barrier, formed by the half-metallic ferromagnet La$_{0.7}$Sr$_{0.3}$Mn$_{O3}$ and n-type semiconductor SrTi$_{0.8}$Nb$_{0.2}$O$_3$, 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 SrTiO$_3$ 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 SrTi$_{0.8}$Nb$_{0.2}$O$_3$, especially oxygen vacancies, compared with the conventional insulating SrTiO$_3$ barrier.
Domaines
Physique [physics]
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