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MA: Magnetismus

MA 16: Magn. Kopplungsph
änomene

MA 16.7: Vortrag

Mittwoch, 10. März 2004, 16:45–17:00, H22

90^∘ coupling in (Fe/Cr/Fe)_AFM/Cr/Fe system epitaxially grown on GaAs(001) — •M. Przybylski¹, J. Grabowski¹, W. Wulfhekel¹, M. Rams², and J. Kirschner¹ — ¹Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120 Halle — ²Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Krakow, Poland

Single-crystalline (Fe/Cr/Fe)_AFM/Cr/Fe structures were epitaxially grown on atomically flat GaAs(001). The (Fe/Cr/Fe)_AFM layered antiferromagnet shows an easy-axis of magnetization along the [110] direction which is due to the uniaxial anisotropy existing in the bcc-Fe(001) films grown on GaAs(001). Choosing the same thickness of the antiferromagnetically (AFM) coupled two Fe layers, the net magnetization of the (Fe/Cr/Fe)_AFM is balanced to zero. This holds in particular up to a spin-flop transition when the field is applied along the [110] direction. Adding a second Cr and a third Fe layer of such thicknesses that the top Fe layer is weakly magnetically coupled to the bottom (Fe/Cr/Fe)_AFM structure, low field MOKE and SQUID magnetization loops show reversal in only the top Fe layer of the (Fe/Cr/Fe)_AFM/Cr/Fe structures. In particular, a strong increase of coercivity (by factor of 12) is found at low temperatures. 90^∘ coupling is detected which affects the minor loops measured along the [-110] and [100] direction.