Epitaxial strain, metastable structure, and magnetic anisotropy in Co-based superlattices (invited)

We explore the relationship between interface structure and magnetic anisotropy in three types of Co-based superlattices: Cohcp-AU; Cofcc-Cu; and CohcP-Cr, grown epitaxially on GaAs( 110). For very thin layers of Co, Co-Au, and Co-Cu superlattices exhibit a perpendicular easy axis due to magnetoelastic contributions to the anisotropy energy. The magnetic anisotropy in Co-Cr is found to be strongly dependent on growth conditions. At slow deposition rates of Co the interface between Co and Cr becomes diffuse as is evidenced by a low saturation moment and a shift toward perpendicular anisotropy whereas samples with abrupt interfaces show predominantly parallel anisotropy. The Cr layers grow in a metastable hcp phase which appears to be paramagnetic. The results illustrate the influence of the heterointerface on magnetic properties.