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Atomic-Scale Study of a Co/AlOx/Co Magnetic Tunnel Junction

Published online by Cambridge University Press:  02 July 2020

M.J. Plisch ,
J.L. Chang ,
M.J. Plisch  and
R.A. Buhrman
M.J. Plisch
Affiliation:
School of Applied and Engineering Physics, Cornell University, Ithaca, NY, 14853
J.L. Chang
Affiliation:
School of Applied and Engineering Physics, Cornell University, Ithaca, NY, 14853
M.J. Plisch
Affiliation:
School of Applied and Engineering Physics, Cornell University, Ithaca, NY, 14853
R.A. Buhrman
Affiliation:
School of Applied and Engineering Physics, Cornell University, Ithaca, NY, 14853
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Abstract

Magnetic tunnel junctions (MTJ) which consist of two ferromagnetic electrodes separated by a thin (∼10Å) tunnel barrier can exhibit a magnetoresistance of greater than 40% at 295 K. They hold substantial potential for application as computer memory and magnetic field sensors. Much about the spin-dependent tunneling process is still not understood. in order to identify features that may affect the spin-polarization of the tunnel current, we have used the UHV STEM at Cornell University to perform atomic-scale imaging and EELS on an MTJ system. The MTJ was sputter deposited on (100) Si with layer sequence Co 60Å/Al 12AÅO2 exposure/Co 100Å.

The annular dark field (ADF) image (Fig. la) shows the A10x barrier layer has a fairly uniform thickness of about 15 Å. Its profile (Fig. 1c) appears diffuse partly due to layer roughness rather than atomic mixing. in bright field (BF) the appearance of strong Fresnel fringes (Figs. 1b,c), due to a large difference in average electrostatic potential between Co and AlOx, complicates interpretation.

Type
Quantitative STEM: Imaging and EELS Analysis Honoring the Contributions of John Silcox (Organized by P. Batson, C. Chen and D. Muller)
Information
Microscopy and Microanalysis , Volume 7 , Issue S2: Proceedings: Microscopy & Microanalysis 2001, Microscopy Society of America 59th Annual Meeting, Microbeam Analysis Society 35th Annual Meeting, Long Beach, California August 5-9, 2001 , August 2001 , pp. 196 - 197
Copyright
Copyright © Microscopy Society of America 2001

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