Giant magnetoresistance and microstructural characteristics of epitaxial Fe-Ag and Co-Ag granular thin films

Journal Article · Sun May 15 04:00:00 EDT 1994 · Journal of Applied Physics; (United States)

DOI:https://doi.org/10.1063/1.356774· OSTI ID:7274448

Thangaraj, N; Echer, C; Krishnan, K M ^[1]; Farrow, R F.C.; Marks, R F; Parkin, S S.P. ^[2]

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1. Materials Sciences Division, Lawrence Berkeley Laboratory, University of California, Berkeley, California 94720 (United States)
2. IBM Research Division, Almaden Research Center, 650 Harry Road, San Jose, California 95120-6099 (United States)

The microstructure and magnetic properties of phase-separated Fe-Ag and Co-Ag granular alloy films, grown epitaxially on (001) NaCl substrates and exhibiting giant magnetoresistance (GMR), have been investigated. Surprisingly, two Fe-Ag films of similar composition grown under identical conditions are found to have substantially different microstructures yet display similar GMR. The microstructure of the films is characterized by Fe-rich or Co-rich regions, respectively, 350--700 nm in extent, surrounded by a Ag-rich matrix. Within the Ag-rich regions, the Fe concentration varies from 20 to 25 at % and the Co concentration is [congruent]16 at %. Within these regions essentially pure fcc Co particles and bcc Fe particles are in parallel and rotated epitaxial alignment respectively with the fcc silver matrix. The Co and Fe particles are [congruent]15--25 A in diameter. It is these small particles which most likely account for the giant magnetoresistance exhibited by these alloys. This suggests that a size distribution of magnetic particles, sharply peaked at the optimum size with limited bulk segregation, might give rise to larger GMR values.

• DOE Contract Number: AC03-76SF00098
• OSTI ID: 7274448
• Journal Information: Journal of Applied Physics; (United States), Journal Name: Journal of Applied Physics; (United States) Vol. 75:10; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
360104 -- Metals & Alloys-- Physical Properties
ALLOY SYSTEMS
ALLOYS
BINARY ALLOY SYSTEMS
COBALT ALLOYS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
FILMS
GRANULAR MATERIALS
IRON ALLOYS
MAGNETORESISTANCE
MATERIALS
MICROSTRUCTURE
PHYSICAL PROPERTIES
SILVER ALLOYS
THIN FILMS