Effect of interlayer boundaries on the optical and magnetooptic properties of a thin-film periodic Fe/Al system

Optical and magnetooptic properties of a multilayer thin-film Fe/Al system were studied in a range of 0.25-7 μm by ellipsometry and transverse magnetooptic Kerr effect (TKE). Samples with Fe layers of a constant thickness (d Fe = 21 A) and Al layers of variable thickness (d Al = 4-30 A) were prepared by high-frequency sputtering onto Si(100) substrates. The spectral dependence of the effective optical conductivity σ eff and TKE were analyzed in the framework of a phenomenological theory developed for layered structures with allowance for the transient layer formed at the interface between the different metallic media. The completely developed transition layer was established to be nonmagnetic and to have a thickness of D t ≅ 14 A. If the Al layer thickness is less than 14 A, the aluminum completely dissolves in the iron, forming a compositionally nonuniform transition layer. The main features of the field dependence of TKE in Fe/Al system with d Al = 14 and 30 A are interpreted on the assumption that a supermagnetic phase is formed in the transition layers.