S G Wang et al 2009 J. Phys. D: Appl. Phys. 42 225001 doi:10.1088/0022-3727/42/22/225001
S G Wang1,6, A Kohn2,5, C Wang2, A K Petford-Long2,7, S Lee3, R Fan3, J P Goff3,8, L J Singh4, Z H Barber4 and R C C Ward1,5
Show affiliationsExchange bias has been studied in epitaxial Fe/Ir0.2Mn0.8 (IrMn) bilayers grown by molecular beam epitaxy on MgO (0 0 1) substrates. The IrMn layer has a chemically disordered fcc structure with an epitaxial relationship of MgO(0 0 1)[1 1 0]//Fe(0 0 1)[1 0 0]//IrMn(0 0 1) [1 1 0]. In this system, exchange bias is induced during growth at room temperature without post-annealing, by applying a small magnetic field, HA, along the bcc Fe [1 0 0] easy axis. The temperature dependence of the exchange bias field and the coercivity along the Fe [1 0 0] easy axis, measured up to approximately half the Néel temperature, shows an exponential decay of these parameters with increasing temperature. The magnetization measured as a function of applied field along the Fe [1 0 0] easy axis results in a negatively shifted hysteresis loop, typical for exchange bias, while when the magnetic field is applied along the Fe [0 1 0] easy axis (perpendicular to HA), a symmetric double-shifted loop is observed. In both cases, the magnetization reversal occurs through two successive events involving nucleation and propagation of domains in which the magnetic moments are perpendicular to each other. We demonstrate that due to the epitaxial growth of the IrMn layer, the unidirectional anisotropy induced by exchange bias is aligned with one of the Fe easy axis directions and, in effect, is added to the four-fold cubic anisotropy of the Fe layer.
68.55.A- Nucleation and growth
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
Issue 22 (21 November 2009)
Received 10 July 2009, in final form 23 September 2009
Published 27 October 2009
S G Wang et al 2009 J. Phys. D: Appl. Phys. 42 225001
F Song et al 2009 Smart Mater. Struct. 18 125007
Decio Levi and Christian Scimiterna 2009 J. Phys. A: Math. Theor. 42 465203
R C Andrew and H G Miller 2008 J. Phys. A: Math. Theor. 41 158001
2008 J. Phys.: Conf. Ser. 188 011002
J Voll and R de Vivie-Riedle 2009 New J. Phys. 11 105036
Oleg Korobkin et al 2009 Class. Quantum Grav. 26 145007
Dmitry Batenkov 2009 Inverse Problems 25 105001
S N Taraskin 2007 J. Phys.: Condens. Matter 19 455215
Katarzyna Grabowska and Janusz Grabowski 2008 J. Phys. A: Math. Theor. 41 175204