Structural and Magnetic Properties of Co-Fe Binary Alloy Monolayers on W(110)

Abstract

We present an experimental investigation of CoxFe1-x monolayers grown on flat and stepped W(110) surfaces. Atomically resolved scanning tunneling microscopy and low energy electron diffraction reveal continuous miscibility and pseudomorphic growth of Co and Fe for 0<or=x<0.6. We observe short range ordered CoFe3-p(2x2) and CoFe-c(2x2) structures in the pseudomorphic monolayer. High Co concentrations lead to a phase separation. The Curie temperature and the ferromagnetic Kerr signal at low temperatures decrease monotonically with increasing Co concentration, finally vanishing at x=0.5.

High magnetic moments and anisotropies forFexCo1−xmonolayers on Pt(111)

“…In that case the authors observed a monotonically decreasing Curie temperature with increasing the Co concentration. 46 This was ascribed to the Fe-Co hybridization which, in this peculiar system, reduces the tendency toward ferromagnetic ordering with increasing Co content.…”

Heteroeptiaxial growth of alloy monolayers on W(110)

“…At an intermediate temperature (510 K) one even obtains ordered alloy structures as shown by LEED (see Fig. 6) and STM [9]. However, the comparatively large width of the superstructure spots observed by electron diffraction indicates that the order in this case is of short-range nature.…”

“…Deposition of small amounts of Co at room temperature followed by annealing leads to a fundamentally different morphology in comparison to the deposition at high substrate temperatures. In contrast to sequential deposition a codeposition of both elements results in an ordered or random alloy depending on the growth temperature [9].…”

“…The dependence of magnetic and electronic properties of 3d metal bulk alloys on their composition has been studied since a very long time. The properties of bulk alloys may be severely altered by the strong substrate-film interaction in the ultrathin film regime [8][9][10].…”

Magnetic and structural investigations of ultra-thin Co–Fe alloy films on W(1 1 0)

“…The W(1 1 0) crystal consisted of a flat and a vicinal part with atomic steps along the [0 0 1] direction and a terrace width of 9:1 nm: The alloy films with a thickness of 1.8-7 monolayer (ML) were deposited at room temperature. Pseudomorphic growth and continuous miscibility of Co x Fe 1Àx monolayers was shown for xo0:6 by scanning tunneling microscopy (STM) and low energy electron diffraction (LEED) [5]. Higher Co concentrations led to a phase separation of Co-rich segregations, which are grown in Nishiyama-Wassermann orientation on the substrate.…”