Buffer-Layer Dependence of Interface Magnetic Anisotropy in Co2Fe0.4Mn0.6Si Heusler Alloy Ultrathin Films

Buffer-layer dependences of dead-layer thickness, saturation magnetization (Ms), and interface magnetic anisotropy (K
_s
) were systematically investigated for Co
₂
Fe
_0.4
Mn
_0.6
Si (CFMS) Heusler alloy ultrathin films with Pd, Ru, and Cr buffer layers. Perpendicular magnetization was only achieved in 0.6 and 0.8 nm-thick CFMS ultrathin films deposited on Pd buffer layer and annealed at 400 °C. At the optimum annealing temperature of 400 °C, Ks of 1.2 erg/cm
²
was obtained for the Pd buffer layer, which was 3-6 times larger than those for Ru and Cr buffer layers. The difference in Ks probably originates from the interdiffusion and different crystallized compounds at the interface between Pd (Ru, Cr) and CFMS layers.