Dresden 2003 – wissenschaftliches Programm
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MA: Magnetismus
MA 30: Spinabh
ängige Transportph
änomene II
MA 30.1: Vortrag
Freitag, 28. März 2003, 10:45–11:00, HSZ/401
Antiferromagnetically coupled Spin Valves with Spacer Layer Thickness down to 1nm — •Tobias Hempel1,2, Inga Ennen1, Andreas Hütten1, and Günter Reiss1 — 1University of Bielefeld, Department of Physics, Universitätsstrasse 25, 33615 Bielefeld, Germany — 2HL Planartechnik GmbH, Hauert 13, 44227 Dortmund, Germany
The GMR amplitude of a given spin valve structure strongly depends on the thickness tNM of the nonmagnetic spacer layer. The GMR amplitude can be expressed phenomenologically as Δ R / R (tNM) ∼ exp (−tNM / lNM) / ( 1 + tNM / t0 ) [1]. Here, lNM is related to the mean-free path of the conduction electrons, t0 is an effective thickness representing the shunting. Consequently, the largest MR amplitudes are obtained for spacer layers as thin as possible. Since the pioneering work of Th. G. S. Rijks et. al. [2] and B. Dieny et. al. [3] it is generally believed that there is a critical interlayer thickness about 1.5nm, below which no perfect antiparallel alignment of the magnetization of a exchange biased spin valve can be realized. High ferromagnetic coupling, possibly caused by pinholes or orange peel coupling results in a parallel alignment of the pinned and free layer regardless of the external field.
It is the objective of this study to demonstrate that in well grown trilayers of the type NiFe-Co/Cu/Co/IrMn the RKKY-like antiferromagnetic coupling is dominating the ferromagnetic coupling down to a spacer layer thickness of about 1nm with GMR effect amplitudes of about 10%.
[1] B. Dieny, J. Magn. Magn. Mater. 136, p. 335 (1994)
[2] Th. G. S. M. Rijks et. al., J. Appl. Phys. 76, p. 1092 (1994)
[3] B. Dieny et al., J. Appl. Phys. 69, p. 4774 (1991)