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Title: Tuning the ferromagnetic-antiferromagnetic interfaces of granular Co-CoO exchange bias systems by annealing

The low-temperature magnetic behavior of granular Co-CoO exchange bias systems, prepared by oxygen ion implantation in Co thin films and subsequent annealing, is addressed. The thermal activation effects lead to an O migration which results in virtually pure Co areas embedded in a structurally relaxed and nearly stoichiometric CoO phase. This yields decreased training and exchange bias shifts, while the blocking temperature significantly increases, coming close to the Néel temperature of bulk CoO for samples implanted to a fluence above 1 × 10{sup 17} ions/cm{sup 2} (15% O). The dependence of the exchange bias shift on the pristine O-implanted content is analogous to that of the antiferromagnetic thickness in most ferromagnetic/antiferromagnetic systems (i.e., an increase in the exchange bias shift up to a maximum followed by a decrease until a steady state is reached), suggesting that, after annealing, the enriched Co areas might be rather similar in size for samples implanted above 1 × 10{sup 17} ions/cm{sup 2}, whereas the corresponding CoO counterparts become enlarged with pristine O content (i.e., effect of the antiferromagnet size). This study demonstrates that the magnetic properties of granular Co-CoO systems can be tailored by controllably modifying the local microstructure through annealing treatments.
Authors:
; ; ; ;  [1] ;  [1] ;  [2] ;  [3]
  1. Instituut voor Kern- en Stralingsfysica, KU Leuven, Celestijnenlaan 200 D, BE-3001 Leuven (Belgium)
  2. (UFRGS), Porto Alegre, 91501-970 Rio Grande do Sul (Brazil)
  3. Instituto de Física, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, 91501-970 Rio Grande do Sul (Brazil)
Publication Date:
OSTI Identifier:
22273656
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 13; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ANNEALING; ANTIFERROMAGNETIC MATERIALS; ANTIFERROMAGNETISM; COBALT; COBALT OXIDES; FERROMAGNETIC MATERIALS; FERROMAGNETISM; INTERFACES; ION IMPLANTATION; MAGNETIC PROPERTIES; MICROSTRUCTURE; OXYGEN IONS; TEMPERATURE DEPENDENCE; THIN FILMS