%0 Journal Article
%A Galceran, R.
%A Balcells, Ll.
%A Martínez-Boubeta, C.
%A Bozzo, B.
%A Cisneros-Fernández, J.
%A Mata, M. de la
%A Magén, C.
%A Arbiol, J.
%A Tornos, J.
%A Cuéllar Jiménez, Fabian Andrés
%A Sefrioui, Zouhair
%A Cebollada, A.
%A Golmar, F.
%A Huesos, L.E.
%A Casanova, F.
%A Santamaría Sánchez-Barriga, Jacobo
%A Martínez, B.
%T Interfacial effects on the tunneling magnetoresistance in La_(0.7)Sr_(0.3)MnO_(3)/MgO/Fe tunneling junctions
%D 2015
%@ 1098-0121
%U https://hdl.handle.net/20.500.14352/24217
%X We report on magnetotransport properties on La_(0.7)Sr_(0.3)MnO_(3)/MgO/Fe tunnel junctions grown epitaxially on top of (001)-oriented SrTiO_(3) substrates by sputtering. It is shown that the magnetoresistive response depends critically on the MgO/Fe interfacial properties. The appearance of an FeOX layer by the interface destroys the 1 symmetry filtering effect of the MgO/Fe system and only a small negative tunneling magnetoresistance (TMR) (∼ −3 %) is measured. However, in annealed samples a switchover from positive TMR (∼ +25% at 70 K) to negative TMR (∼ −1 %) is observed around 120 K. This change is associated with the transition from semiconducting at high T to insulating at low T taking place at the Verwey transition (TV ∼ 120 K) in Fe3O4, thus suggesting the formation of a very thin slab of magnetite at the MgO/Fe interface during annealing treatments. These results highlight the relevance of interfacial properties on the tunneling conduction process and how it can be substantially modified through appropriate interface engineering.
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