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Incidence of in-situ annealing on the nanoscale topographical/electrical properties of tunnel barrier in sputtered epitaxial Fe/MgO/Fe multilayers

D J Kim, J Arabski, V Da Costa, G Schmerber, M Bowen, S Boukari and E Beaurepaire
IPCMS UMR 7504 CNRS, Université de Strasbourg,
23 Rue du Loess, BP 43, 67034 Strasbourg Cedex 2, France
E-mail: dong-jik.kim@ipcms.u-strasbg.fr

[(D J Kim) and]

eric.beaurepaire@ipcms.u-strasbg.fr

(E Beaurepaire)

Abstract. Technological improvements in the magnetotranport performance of Fe/MgO/Fe stacks require nanoscale control over the topographical and electrical properties of the ultrathin MgO barrier. We have statistically investigated the incidence of in-situ annealing of the lower Fe layer on the nanoscale topographical/electrical properties of Fe/MgO bilayers and the structural and magnetic properties of Fe/MgO/Fe/Co multilayers prepared by sputtering. This annealing step improves the crystal quality of both the lower Fe and upper Fe/Co layers, leading to an enhanced saturated magnetic moment. Finally, this annealing step substantially mitigates the presence of nanohills on the lower Fe layer and improves the uniformity of the height and/or the thickness of MgO tunnel barrier. Our results pave the way for studies of nanoscale transport on micron-sized devices through a better understanding of, and control over, nanoscale hotspots in the tunnel barrier.

PACS numbers: 85.75.Dd, 81.15.-z, 68.55.-a

[Submitted to: J. Phys. D: Appl. Phys.]

[in-situ annealing on Fe/MgO/Fe multilayers]

[2]

1. Introduction