International Conference on Nanoscale Magnetism 2013, İstanbul, Turkey, 2 - 06 September 2013, pp.256
Conference Paper / Full Text
Structural Origins of the Training Effect In NiFe/IrMn/CoFe Exchange Bias Trilayers
R. Mustafa Oksuzoglu*, S. Pekdemir, M. Emre Sancı, M. Yıldırım, O. Deniz
Department of Materials Science and Engineering, Anadolu University, 26480, Eskisehir, Turkey
The exchange bias (EB) effect originated from the magnetic interfacial interaction between
an antiferromagnetic (AF) and a ferromagnetic (F) layer is indispensable in magnetic data storage
systems. Therefore, EB phenomenology is still investigated in many aspects since its discovery .
The underlying mechanism and the role of the interface/bulk structure have been investigated in a
variety of EB systems [2-4] with different deposition techniques and F/AF materials. An important
phenomenon for storage application in EB systems is the training effect; a gradual degradation of
the EB field can take place when cycling the heterostructure through consecutive hysteresis loops
. This aging phenomenon is known as training effect and is affected by several factors as
temperature, AF thickness, anisotropy field, interface roughness, cooling field, dilution, and
structure of AF/F materials [6-8]. Not only understanding of the underlying mechanism of the EB
effect, but also the quenching of the training effect is crucial for application.
In the present study, we worked on NiFe/IrMn/CoFe based EB trilayer systems with Ta/Ru
buffer/seed layers, which were deposited by pulsed DC unbalanced magnetron sputtering technique,
in order to investigate the effects of the interfacial roughness variations and grain size of the IrMn
layer on the EB properties and training effect. The interface roughness is systematically varied
without any change in the thickness and grain size of IrMn layer enabling investigation of the
influence of the roughness on both EB and training effects. Additionally, the grains size of the IrMn
layer is systematically varied without any change in the thickness of the IrMn layer, in order to
study the relationship between grain size and EB and training effects. Structural origins of the
training effects besides of the origin of the EB in NiFe/IrMn/CoFe based EB trilayer systems were
 W.H. Meiklejohn, C.P. Bean, Phys. Rev. 102 (1956) 1413.
 R. M. Öksüzoğlu, M. Yıldırım, H. Çınar, E. Hildebrandt, L. Alff, J. Magn. Magn. Mater. 323
 R. Mustafa Öksüzoğlu, Özlem Akman, Mustafa Yıldırım, Bekir Aktaş, Journal of Magnetics,
17(4), 245-250 (2012).
 K. O‘Grady, L.E. Fernandez-Outon, G. Vallejo-Fernandez, J. Magn. Magn Mater. 322 (2010)
 Srinivas Polisetty, Sarbeswar Sahoo, and Christian Binek, Phys. Rev. B 76 (2007) 184423.
 Andreas Biternas PhD-Thesis, ?Study of the training effect in exchange bias using the domain
state model?, University of York, Department of Physics (2009).
 L.E. Fernandez-Outon, G. Vallejo-Fernandez, Sadia Manzoor1, K. O‘Grady, Journal of
Magnetism and Magnetic Materials 303 (2006) 296–301.
 A. Kohn, J. Dean et al. Journal of Applied Physics 109 (2011) 083924.