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Spectroscopic and transport studies ofCoxFe1−x/MgO(001)-based magnetic tunnel junctions

Spectroscopic and transport studies ofCoxFe1−x/MgO(001)-based magnetic tunnel junctions

Authors :
Frédéric Bonell
Stéphane Andrieu
Thomas Hauet
L. Calmels
François Bertran
P. Le Fèvre
Source :
Physical Review B. 90
Publication Year :
2014
Publisher :
American Physical Society (APS), 2014.

Abstract

${\mathrm{Fe}}_{1\ensuremath{-}x}{\mathrm{Co}}_{x}$ epitaxial layers were grown by molecular beam epitaxy and controlled using in situ characterization tools (electron diffraction, x-ray photoelectron, and Auger spectroscopies) in order to use these alloys in magnetic tunnel junctions. Thick films are shown to be BCC up to $x=70$%, whereas thin films grown on Fe(001) are BCC over the whole Co concentration range up to a critical thickness. Fe/Co intermixing is also examined in detail. The tunnel magnetoresistance and conductance of MgO-based magnetic tunnel junctions built with BCC ${\mathrm{Fe}}_{1\ensuremath{-}x}{\mathrm{Co}}_{x}$ electrodes show peculiar voltage dependencies. Their interpretation relies on spin- and symmetry-resolved photoemission measurements and ab initio calculations. The bulk and interfacial occupied states detected by photoemission are compared to the calculated ones. Experimental results and ab initio calculations are in good agreement. Finally, the experimental conductance curves are compared to the autoconvolution of the $\ensuremath{\Delta}1$ density of states in which both bulk and interface states are taken into account.

Details

ISSN :
1550235X and 10980121
Volume :
90
Database :
OpenAIRE
Journal :
Physical Review B
Accession number :
edsair.doi...........767f9c586ae379ebe6ca24e406e480a1
Full Text :
https://doi.org/10.1103/physrevb.90.214406