scholarly journals Response to “Comment on ‘Thickness and angular dependencies of exchange bias in ferromagnetic/antiferromagnetic bilayers’ [J. Appl. Phys. 92, 1009 (2002)] and ‘Thickness dependence of exchange bias and coercivity in a ferromagnetic layer coupled with an antiferromagnetic layer’ [J. Appl. Phys. 94, 2529 (2003)]”

2004 ◽  
Vol 96 (3) ◽  
pp. 1765-1766
Author(s):  
Jing-guo Hu ◽  
Guo-jun Jin ◽  
Yu-qiang Ma
2002 ◽  
Vol 746 ◽  
Author(s):  
Markus Kirschner ◽  
Dieter Suess ◽  
Thomas Schrefl ◽  
Josef Fidler

ABSTRACTExchange bias and training effect are simulated for IrMn/NiFe bilayers. As a function of the thickness of the antiferromagnet the bias field shows a maximum for a thickness of 22 nm. For decreasing antiferromagnetic thickness the domain wall energy approaches zero. For large thicknesses the high anisotropy energy hinders switching of the antiferromagnetic grains resulting in weak bias. Starting from the field cooled state as initial configuration a bias field of about 8 mT is obtained assuming a antiferromagnetic layer thickness of 20 nm, a ferromagnetic layer thickness of 10 nm, and a grain size of 10 nm. The next hysteresis cycle shows a reduction of the bias field by about 65%. Exchange bias and training effect in fully compensated antiferromagnet/ferromagnet bilayers are explained with a simple micromagnetic model. The model assumes no defects except for grain boundaries, and coupling is due to spin flop at a perfect interface. The simulations show that a weak exchange interaction between randomly oriented antiferromagnetic grains and spin flop coupling at a perfectly compensated interface are sufficient to support exchange bias.


2002 ◽  
Vol 746 ◽  
Author(s):  
U. Nowak ◽  
A. Misra ◽  
K. D. Usadel

ABSTRACTThe domain state model for exchange bias consists of a ferromagnetic layer exchange coupled to an antiferromagnetic layer. In order to model a certain degree of disorder within the bulk of the antiferromagnet, the latter is diluted throughout its volume. Extensive Monte Carlo simulations of the model were performed in the past. Exchange bias is observed as a result of a domain state in the antiferromagnetic layer which develops during the initial field cooling, carrying a remanent domains state magnetization which is partly irreversible during hysteresis. A variety of typical effects associated with exchange bias like, e. g., its dependence on dilution, positive bias, temperature and time dependences as well as the dependence on the thickness of the antiferromagnetic layer can be explained within this model.


2011 ◽  
Vol 675-677 ◽  
pp. 1263-1266
Author(s):  
Jian Wang ◽  
Shinji Muraishi ◽  
Ji Shi ◽  
Yoshio Nakamura

We have used ferromagnet/antiferromagnet/ferromagnet sandwich structure to probe the antiferromagnetic layer thickness dependence of exchange bias in sputter-deposited Co/CoO/Co trilayer. The exchange coupling occurring at the upper ferromagnetic/antiferromagnetic interface is always found to be stronger than the one at the lower antiferromagnetic/ferromagnetic interface. The grain growth with increasing antiferromagnetic layer thickness can lead to a gradient of grain size distribution through the whole antiferromagnetic layer. Consequently, the relatively large grains at the upper interface would results in a rougher interface which we treat as structural defects and can significantly enhance exchange bias through domain state model. The slightly decrease of exchange coupling with increasing antiferromgnetic layer thickness indicates that the exchange bias is only governed by the grains that are thermally stable but whose anisotropy energy is low enough to be set.


2020 ◽  
Vol 12 (5) ◽  
pp. 701-706
Author(s):  
Liyan Wang ◽  
Zongguo Li ◽  
Cong Wang ◽  
Xue Gong ◽  
Changzheng Wang

Many of researches indicate that epitaxial BiFeO3 (BFO) films deposited on LaAlO3 (LAO) substrate undergo strain-driven phase transition from a tetragonal-like phase (T-BFO) to a rhombohedral-like phase (R-BFO), and a mixed phase (M-BFO) that T-BFO coexists with R-BFO forms in the phase transition process. It is necessary to explore how BFO phase transition affects the exchange bias in ferromagnet (FM)/BFO bilayers. In our studies, aforementioned BFO phase transition is accomplished by varying BFO films thickness. Using 5 nm-thick Fe as ferromagnetic layer deposited on 9–354 nm-thick BFO as antiferromagnetic layer, the exchange bias in Fe/BFO bilayers exhibits that Fe/M-BFO bilayers shows smaller exchange bias than Fe/T-BFO and Fe/R-BFO bilayers. We ascribed the effect of the BFO phase transition on the exchange bias to the domain walls caused by the exchange interaction between T-BFO and R-BFO across their boundaries. Additionally, for the same reason, the coercivity also exhibits the same variation trend as the exchange bias does. Our studies will help to promote the application of controlling the ferromagnetic magnetization by the electric field.


2003 ◽  
Vol 68 (21) ◽  
Author(s):  
M. Ali ◽  
C. H. Marrows ◽  
M. Al-Jawad ◽  
B. J. Hickey ◽  
A. Misra ◽  
...  

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