Interface structure and magnetism of Fe₃Si/GaAs(110) multilayers: An ab-initio study

Abstract

Ferromagnet-semiconductor (FM/SC) hybrid structures have attracted much interest in view of materials being suitable for spintronic devices. Such devices demand a high spin-polarization at the FM/SC interface, as is provided by Fe₃Si. Here, we investigate the hybrid system consisting of Fe₃Si and GaAs which is of special interest due to its tiny lattice mismatch. The multilayers containing 1–3 layer thick Fe₃Si films are oriented in the (110) direction. Using the (110) orientation of GaAs has the advantage that no surface reconstruction has to be considered. Free GaAs(110) surfaces show only a rippling but no reconstruction. We investigate the structural and magnetic properties of thin layers of Fe₃Si on GaAs(110) using density functional theory. Therefore we choose a multilayer geometry in order to avoid additional contributions from the surface. The ground state structure turns out to be the same, independently of the number of FM layers, and the rippled GaAs(110) surface is flattened if overgrown by Fe₃Si. Moreover, we find the system being stable against diffusion effects which leads to average magnetic moments of the magnitude of bulk Fe₃Si. Concerning the magnitude of the magnetic moments, our calculations suggest that Fe₃Si/GaAs(110) may be a good candidate for magnetoelectronics.

Keywords:

• ab-initio
• electronic structure
• Fe-based alloys
• GaAs
• interfaces
• magnetic films
• multilayer

Acknowledgements

We would like to thank M.E. Gruner for reading the manuscript. This work has been supported by the Deutsche Forschungsgemeinschaft through the SFB 491 ‘Spin Structure and Spin Transport in Magnetic Heterostructures’.