Finite-size effects in amorphous Fe90Zr10/Al75Zr25 multilayers

TL;DR

This study investigates how the magnetic properties of amorphous Fe90Zr10 layers in multilayers change with thickness, revealing a critical size below which ferromagnetism vanishes, using finite-size scaling analysis.

Contribution

It provides the first detailed analysis of finite-size effects on magnetic ordering in amorphous Fe90Zr10 multilayers, establishing a critical thickness and scaling behavior.

Findings

Curie temperature decreases non-linearly with decreasing layer thickness.

No ferromagnetic order observed below 6.5 Å thickness.

Finite-size scaling formula fits the variation of Curie temperature.

Abstract

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 {\AA} 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.