X-ray study of the relation between the coercivity and atomic structural properties of the epitaxial Co/Pt multilayers on Al₂O ₃(11-20) substrates

The relation between the coercivity and the structure of MBE (Co/Pt) ₃₀ multilayers on Al₂O₃ (11-20) with Pt buffer layers was studied. By changing the thickness of Co layers, Pt layers or Pt buffer layers, the in-plane strains of Pt layers can be varied from -1.6% to -4.5%. The coercive force, H_c, is roughly inverse proportional to the in-plane strain of Pt layer. However, if the in-plane strain is constant, the H_c is still increased regardless of the decrease of the density of the in-plane defects as the thickness of the Pt buffer layer increases. The interface mixing might be the reason of reducing the H_c value.