Temperature dependence of the training effect in electrodeposited Co/CoO nanotubes

• Type: Article in International Scientific Journal
• Date: 2013

Authors

proenca, m. p. (Author) FCUP; ventura, j. (Author) FCUP; sousa, c. t. (Author) Other; vazquez, m. (Author) Other; araujo, j. p. (Author) FCUP

Journal

Title: Journal of Applied Physics

Vol. 114

Final page: 043914

ISSN: 0021-8979

Publisher: American Institute of Physics

Indexing

ISI Web of Knowledge - 7 Citations

Scopus - 9 Citations

Other information

Authenticus ID: P-006-936

DOI: 10.1063/1.4816696

Abstract (EN): High aspect ratio Co/CoO nanotubes (NTs) were obtained by potentiostatic electrodeposition of Co inside nanoporous alumina templates followed by the natural oxidation of their inner walls. Magnetic measurements performed at low temperatures after field cooling the samples from above its blocking temperature (T-B similar to 220 K), evidenced the existence of exchange bias (EB) coupling between the Co ferromagnetic outer wall and the CoO antiferromagnetic inner wall of the NTs. A decrease in the magnitude of the EB field was measured at T < T-B when cycling the Co/CoO NT arrays through consecutive hysteresis loops. This decrease is known as the training effect (TE) and is here studied in the 6 K <= T < T-B temperature range. The TE was fitted using the recursive Binek formula, giving small values for the characteristic decay rate of the training behavior, and evidencing a decrease of EB with increasing antiferromagnetic layer thickness. A phenomenological theory for the temperature dependence of the TE in exchange biased systems was applied for the first time to core-shell nanotubular structures. The good agreement obtained between the experimental results and the theoretical data, provided a strong confirmation of the qualitative correctness of the spin configuration relaxation model used in these systems. (C) 2013 AIP Publishing LLC.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 5