Unified nonequilibrium dynamical theory for exchange bias and training effects
Zhang Kai-Cheng(张开成)† and Liu Bang-Gui(刘邦贵)
Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China Beijing National Laboratory for Condensed Matter Physics, Beijing 100190, China
Abstract We have investigated the exchange bias and training effect in the ferromagnetic/antiferromagnetic (FM/AF) heterostructures using a unified Monte Carlo dynamical approach. The magnetization of the uncompensated AF layer is still open after the first field cycling is finished. Our simulated results show obvious shift of hysteresis loops (exchange bias) and cycling dependence of exchange bias (training effect) when the temperature is below 45 K. The exchange bias field decreases with decreasing cooling rate or increasing temperature and the number of the field cycling. Essentially, these two effects can be explained on the basis of the microscopical coexistence of both reversible and irreversible moment reversals of the AF domains. Our simulations are useful to understand the real magnetization dynamics of such magnetic heterostructures.
Received: 08 March 2009
Revised: 25 March 2009
Accepted manuscript online:
PACS:
75.70.Cn
(Magnetic properties of interfaces (multilayers, superlattices, heterostructures))
(Domain structure (including magnetic bubbles and vortices))
Fund: Project supported by the National
Natural Science Foundation of China (Grant Nos 10874232, 10774180
and 60621091), the Chinese Academy of Sciences (Grant No
KJCX2.YW.W09-5), and the Ministry of Science and Technology, China
(Grant No 2005CB623602).
Cite this article:
Zhang Kai-Cheng(张开成) and Liu Bang-Gui(刘邦贵) Unified nonequilibrium dynamical theory for exchange bias and training effects 2009 Chin. Phys. B 18 3960
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