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Structural Studies of Silver/Permalloy and Copper/Permalloy GMR Spin Valve Multilayers

Published online by Cambridge University Press:  10 February 2011

H. Geng
Affiliation:
Department of Materials Science and Mechanics, Michigan State University, East Lansing, MI 48824-1226
W. Zhu
Affiliation:
Department of Materials Science and Mechanics, Michigan State University, East Lansing, MI 48824-1226
J.W. Heckman
Affiliation:
Center for Electron Optics, Michigan State University, East Lansing, MI 48824-1226
R. Loloee
Affiliation:
Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824-1226
W.P. Pratt
Affiliation:
Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824-1226
J. Bass
Affiliation:
Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824-1226
M.A. Crimp
Affiliation:
Department of Materials Science and Mechanics, Michigan State University, East Lansing, MI 48824-1226
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Abstract

Giant magnetoresistance (GMR) spin valves of the form Ag/Py/Ag/Py/FeMn and Cu/FeMn/Py/Cu/Py have been studied using conventional and high-resolution electron microscopy complemented with fast Fourier transform (FFT) diffractogram analysis. Cross-sectional TEM thin foil samples were prepared in order to characterize the layer structures and interfaces. In the Ag/Py system, we have examined a simple spin valve, part of which was grown on the Nb contact and part directly on the Si substrate. The spin valve displays a polycrystalline structure when grown on the Nb contact. In contrast, when grown directly on the Si substrate, the first Ag layer of the spin valve grew as a continuous epitaxial single crystal while the rest of the layers were polycrystalline. Two Cu/Py spin valves, grown on Nb, with 30 nm and 3 nm thick Py layers have been investigated. TEM images reveal good contrast between the Nb contacts and the spin valves, but weak contrast between the individual spin valve layers. Both spin valves displayed columnar, polycrystalline grain structures. HRTEM analysis indicates some non-equilibrium structures exist in the spin valve layers.

Type
Research Article
Copyright
Copyright © Materials Research Society 1998

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