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EELS study of interfaces in magnetoresistive LSMO/STO/LSMO tunnel junctions

  • L. Samet
  • D. ImhoffEmail author
  • J.-L. Maurice
  • J.-P. Contour
  • A. Gloter
  • T. Manoubi
  • A. Fert
  • C. Colliex
Original Paper

Abstract.

A magnetic tunnel junction consists of two ferromagnetic conducting electrodes separated by an insulating thin layer. The performance of such a system strikingly depends on the last conducting atomic layers in contact with the insulator. Consequently, the present paper reports a nanoscale electron energy loss spectroscopy (EELS) study, which has been performed across a couple of La0.66Sr0.33MnO3,/SrTiO3/La0.66Sr0.33MnO3 tunnel junctions with different barrier thickness es (1.5 nm and 5 nm respectively). It aims at determining not only the chemical composition in the interface areas, but also the effect of the neighbouring atoms on their electronic structure. Using recent improvements in the STEM-EELS data acquisition and processing techniques (systematic use of spectrum-line and spectrum-image modes, multivariate statistical analysis, 2D energy deconvolution schemes, etc.), the local chemical information is better extracted with shorter acquisition times, while the large increase of the data set contributes to validate the results. Within the accuracy level of these measurements, the elemental composition of the different phases remains stable up to the interfaces with no evidence of extra doping. Furthermore, weak changes on the Mn-2p edge fine structures (weak shift to lower energy loss values and extra splitting on the top of the Mn L3 line are observed on all the interfaces. They are interpreted as a consequence of a slight reduction of the local Mn valence likely accompanied by a strain induced change in local symmetry. The discussion is focussed on all spectral changes identified at a (sub)nanometer scale and their potential effects on the degradation of magnetic and transport properties measured, close to room temperature, at a macroscopic level.

Keywords

Tunnel Junction Electron Energy Loss Spectroscopy Conducting Electrode Short Acquisition Time Barrier Thickness 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag Berlin/Heidelberg 2003

Authors and Affiliations

  • L. Samet
    • 1
    • 3
  • D. Imhoff
    • 1
    Email author
  • J.-L. Maurice
    • 2
  • J.-P. Contour
    • 2
  • A. Gloter
    • 1
  • T. Manoubi
    • 3
  • A. Fert
    • 2
  • C. Colliex
    • 1
  1. 1.Laboratoire de Physique des Solides, UMR CNRSUniversité Paris-SudOrsayFrance
  2. 2.Laboratoire de Physique des Solides, UMR CNRSUMR de Physique CNRS/ThalèsOrsayFrance
  3. 3.Faculté des Sciences de TunisLPMCTunisTunisia

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