Alloying and strain relaxation effects on spin-reorientation transitions in ${\mathrm{Co}}_{x}{\mathrm{Ni}}_{1\ensuremath{-}x}∕{\mathrm{Cu}}_{3}\mathrm{Au}(100)$ ultrathin films

Alloying and strain relaxation effects on spin-reorientation transitions in ${Co}_{x} {Ni}_{1 - x} ∕ {Cu}_{3} Au (100)$ ultrathin films

W. C. Lin, B. Y. Wang, Y. W. Liao, Ker-Jar Song, and Minn-Tsong Lin

Phys. Rev. B 71, 184413 – Published 25 May 2005

Abstract

The crystalline structure and the magnetic properties of ${Co}_{x} {Ni}_{1 - x} ∕ {Cu}_{3} Au (100)$ films were characterized as functions of thickness and alloy composition. No apparent alloy effect on the crystalline structure was observed with $x$ up to 11%. As the film thickness increases above $\sim 8$ monolayers (ML), the films clearly exhibited a progressively more relaxed structure. Due to the strain relaxation, both the first and the second spin-reorientation transitions (SRT) occurred within 20 ML. The thickness region with perpendicular magnetization was strongly reduced by increasing the Co concentration. For $x > 10 %$ , no SRT was observed. By combining both the alloy effect and the strain relaxation effect, the SRT boundaries in the phase diagram can be described in a phenomenological model on the basis of magnetoelastics.