SUBMONOLAYER MAGNETISM OF FE(110) ON W(110) - FINITE-WIDTH SCALING OF STRIPES AND PERCOLATION BETWEEN ISLANDS

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 theta = 1 to 180 K near theta = 0.1. The decrease scales with 1/theta. Films prepared at 300 K nucleate by islands which start to coalesce near theta = 0.6. For theta less-than-or-equal-to 0.58, they are superparamagnetic at T greater-than-or-equal-to 115 K. In a narrow theta range of only 2%, magnetic percolation occurs, resulting in ferromagnetism with T(c) greater-than-or-equal-to 190 K for theta greater-than-or-equal-to 0.60.