中国物理B ›› 2009, Vol. 18 ›› Issue (9): 3960-3965.doi: 10.1088/1674-1056/18/9/056

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Unified nonequilibrium dynamical theory for exchange bias and training effects

张开成, 刘邦贵   

  1. Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China Beijing National Laboratory for Condensed Matter Physics, Beijing 100190, China
  • 收稿日期:2009-03-08 修回日期:2009-03-25 出版日期:2009-09-20 发布日期:2009-09-20
  • 基金资助:
    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).

Unified nonequilibrium dynamical theory for exchange bias and training effects

Zhang Kai-Cheng(张开成)† and Liu Bang-Gui(刘邦贵)   

  1. Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China Beijing National Laboratory for Condensed Matter Physics, Beijing 100190, China
  • Received:2009-03-08 Revised:2009-03-25 Online:2009-09-20 Published:2009-09-20
  • Supported by:
    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).

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摘要： 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.

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.

Key words: ferromagnetic/antiferromagnetic bilayers, hysteresis, exchange bias, training

中图分类号:  (Magnetic properties of interfaces (multilayers, superlattices, heterostructures))

  • 75.70.Cn
75.30.Cr (Saturation moments and magnetic susceptibilities) 75.30.Et (Exchange and superexchange interactions) 75.50.Ee (Antiferromagnetics) 75.60.Ej (Magnetization curves, hysteresis, Barkhausen and related effects) 75.70.Kw (Domain structure (including magnetic bubbles and vortices))