La0.7Sr0.3MnO3/Bi1-xBaxFeO3接合におけるスピンフィルター効果

概要

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Spin-filter devises were fabricated using multiferroic Bi1-xBaxFeO3 films. La1-xSrxMnO3/Bi1-xBaxFeO3/LaNiO3 junctions showed non-linear current-voltage characteristics with barrier height of 0.37eV and magnetoresistance (MR) of 2.3% at 4.2 K. These results indicate ultra-thin Bi1-xBaxFeO3 layers behaved as ferromagnetic tunnel barriers and showed spin-filter effects. From the analysis of the temperature dependence of current-voltage characteristics of the junctions and the leakage current of Bi1-xBaxFeO3 layers, one of possible reasons for low MR is suppression of spin-filter effects by tunneling through defect levels induced by O and/or Bi deficiency in Bi1-xBaxFeO3 tunnel barriers.