Spectroscopic and transport studies of Cox Fe1-x/MgO(001) -based magnetic tunnel junctions

Stéphane Andrieu (1) , Lionel Calmels (2) , Thomas Hauet (1) , Frédéric Bonell (1) , P. Le Fèvre (3) , F. Bertran (3)

1 IJL - Institut Jean Lamour
2 CEMES-MEM - Matériaux et dispositifs pour l'Electronique et le Magnétisme
3 SSOLEIL - Synchrotron SOLEIL

Fe1-xCox 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 Fe1-xCox 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 Δ1 density of states in which both bulk and interface states are taken into account.

Domaines: Physique [physics]

Stéphane Andrieu, Lionel Calmels, Thomas Hauet, Frédéric Bonell, P. Le Fèvre, et al.. Spectroscopic and transport studies of Cox Fe1-x/MgO(001) -based magnetic tunnel junctions. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2014, 90 (21), pp.214406. ⟨10.1103/PhysRevB.90.214406⟩. ⟨hal-01719199⟩