Enhanced antiferromagnetic exchange coupling in Fe/Si/Fe epitaxial trilayers with Fe0.5Si0.5 boundary layers

Abstract

Epitaxial Fe/Fe0.5Si0.5/Si-wedge/Fe0.5Si0.5/Fe structures are prepared by thermal evaporation with Fe0.5Si0.5 boundary layers grown by coevaporation at 200 °C. Magnetic properties are examined with Brillouin light scattering and longitudinal magneto-optic Kerr effect hysteresis. The interlayer coupling is found to increase in excess of 8 mJ/m2 by introducing a boundary layer at the bottom interface. The coupling maximum shifts from 7 to 3 Å nominal Si thickness. This effect is related to reduced interdiffusion with the formation of an epitaxial, pinhole-free spacer at smaller thickness. Together with the strong increase of the coupling for decreasing spacer thickness, this results in an enhancement of the coupling.