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Observation of inverse magnetoresistance in perovskite oxide tunnel junctions
Author(s) -
Noh J. S.,
Eom C. B.,
Lagally M. G.,
Sun J. Z.,
Kim H. C.
Publication year - 2004
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.200304559
Subject(s) - condensed matter physics , magnetoresistance , quantum tunnelling , ferromagnetism , inverse , tunnel magnetoresistance , materials science , polarization (electrochemistry) , oxide , electrode , spintronics , perovskite (structure) , physics , chemistry , magnetic field , quantum mechanics , crystallography , geometry , mathematics , metallurgy
We have observed a distinct inverse magnetoresistance in a hybrid tunnel junction. Two types of perovskite oxides, La 0.67 Sr 0.33 MnO 3 and SrRuO 3 , were used as ferromagnetic electrodes with an SrTiO 3 barrier in between them. Micron‐scale junctions were fabricated from 90° off‐axis sputtered trilayers, using standard optical lithography. Homo‐junctions that incorporate either La 0.67 Sr 0.33 MnO 3 or SrRuO 3 as both electrodes showed only normal positive magnetoresistances. In contrast, a clear inverse magnetic switching was found at 10 K for the hybrid junction. The spin polarization of SrRuO 3 is about –9% as calculated based upon Julliere model, which is in quantitative agreement with the value (–10%) determined by the earlier tunneling experiment on SrRuO 3 /SrTiO 3 /Al structures. This is not only the manifestation of the existence of a negatively polarized material at the Fermi level, but also demonstrates that the widely‐cited Julliere model is applicable even to a negative polarization case. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)