Unusual ZFC and FC magnetic behavior in thin Co multi-layered structure

The observation of unusual magnetic phenomena in a Ni -based magnetic memory device ([4] O. Ben-Dor et al., 2013) encouraged us to conduct a systematic research on Co based multi-layered structure which contains a α-helix L polyalanine (AHPA-L) organic compound. The constant Co thickness is 7nm and...

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Bibliographic Details
Published in:Journal of magnetism and magnetic materials 2017-04, Vol.428, p.357-361
Main Authors: Ben Dor, Oren, Yochelis, Shira, Felner, Israel, Paltiel, Yossi
Format: Article
Language:English
Subjects:
Chiral magnetic memory
Cobalt
Gold
Magnetic fields
Magnetic properties
Magnetism
Multi-layered thin Co films
Multilayers
Organic chemistry
Organic compounds
Position measurement
Sulfur
Thin films
Unusual Magnetic behavior
ZFC>FC
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Summary:The observation of unusual magnetic phenomena in a Ni -based magnetic memory device ([4] O. Ben-Dor et al., 2013) encouraged us to conduct a systematic research on Co based multi-layered structure which contains a α-helix L polyalanine (AHPA-L) organic compound. The constant Co thickness is 7nm and AHPA-L was also replaced by non-chiral 1-Decanethiol organic molecules. Both organic compounds were chemisorbed on gold by a thiol group. The dc magnetic field (H) was applied parallel and perpendicular to the surface layers. The perpendicular direction is the easy magnetization axis and along this orientation only, the zero-field-cooled (ZFC) plots exhibit a pronounced peak around 55–58K. This peak is suppressed in the second ZFC and field-cooled (FC) runs performed shortly after the virgin ZFC one. Thus, around the peak position ZFC>FC a phenomenon seldom observed. This peak reappears after measuring the same material six months later. This behavior appears in layers with the non-chiral 1-Decanethiol and it is very similar to that obtained in sulfur doped amorphous carbon. The peak origin and the peculiar ZFC>FC case are qualitatively explained. •FC curve crosses ZFC curve in a 7nm Co and thiol-based organic molecules multi-layered structure.•The ZFC>FC phenomena occurs for H perpendicular along the easy axis.•This phenomenon disappears in the second FC-ZFC run performed shortly after.•The unusual behavior reappears after six months.
ISSN:0304-8853
1873-4766
DOI:10.1016/j.jmmm.2016.12.104