Submonolayer magnetism of Fe(110) on W(110): Finite width scaling of stripes and percolation between islands.

Abstract

Relations between magnetism and morphology in submonolayer films of Fe(110) on W(110) were studied using spin polarized electron diffraction and scanning tunneling microscopy. Films prepared at 600 K form monolayer stripes along with the W steps; they are ferromagnetic with ${T}_{c}$ slowly decreasing from 225 K near $\ensuremath{\theta}=1 \mathrm{to} 180$ K near $\ensuremath{\theta}=0.1$. The decrease scales with $\frac{1}{\ensuremath{\theta}}$. Films prepared at 300 K nucleate by islands which start to coalesce near $\ensuremath{\theta}=0.6$. For $\ensuremath{\theta}\ensuremath{\le}0.58$, they are superparamagnetic at $T\ensuremath{\ge}115$ K. In a narrow $\ensuremath{\theta}$ range of only 2%, magnetic percolation occurs, resulting in ferromagnetism with ${T}_{c}\ensuremath{\ge}190$ K for $\ensuremath{\theta}\ensuremath{\ge}0.60$.