Finite-size effects in amorphous Fe90Zr10/Al75Zr25 multilayers

The thickness dependence of the magnetic properties of amorphous Fe90Zr10 layers has been explored using Fe90Zr10/Al75Zr25 multilayers. The Al75Zr25 layer thickness is kept at 40 \AA, while the thickness of the Fe90Zr10 layers is varied between 5 and 20 \AA. The thickness of the Al75Zr25 layers is sufficiently large to suppress any significant interlayer coupling. Both the Curie temperature and the spontaneous magnetization decrease non-linearly with decreasing thickness of the Fe90Zr10 layers. No ferromagnetic order is observed in the multilayer with 5 Å Fe90Zr10 layers. The variation of the Curie temperature \(T_c\) with the Fe90Zr10 layer thickness \(t\) is fitted with a finite-size scaling formula \([1-\Tc(t)/\Tc(\infty)]=[(t-t')/t_0]^{-\lambda}\), yielding \(\lambda=1.2\), and a critical thickness \(t'=6.5\) \AA, below which the Curie temperature is zero.