Growth modes of Fe(110) revisited: a contribution of self-assembly to magnetic materials

Abstract

We have revisited the epitaxial growth modes of Fe on W(110) and Mo(110), and propose an overview or our contribution to the field. We show that the Stranski-Krastanov growth mode, recognized for a long time in these systems, is in fact characterized by a bimodal distribution of islands for growth temperature in the range ∼ 250 − 700 • C. We observe firstly compact islands whose shape is determined by Wulff-Kaischev's theorem, secondly thin and flat islands that display a preferred height, i.e. independant from nominal thickness and deposition procedure (1.4 nm for Mo, and 5.5 nm for W on the average). We used this effect to fabricate self-organized arrays of nanometers-thick stripes by step decoration. Self-assembled nano-ties are also obtained for nucleation of the flat islands on Mo at fairly high temperature, i.e. ∼ 800 • C. Finally, using interfacial layers and solid solutions we separate two effects on the preferred height, first that of the interfacial energy, second that of the continuouslyvarying lattice parameter of the growth surface.

Magnetic imaging with spin-polarized low-energy electron microscopy

“…These results show how the relative importance of different magnetic anisotropy energies contributing to the SRT observed in Fe/W(110) films can be influenced by carefully tuned annealing schedules and by the choice of the substrate atomic step structure. Complementing information on island morphologies and magnetic properties of annealed Fe/W(110) films available from prior studies [119,120], the capability of SPLEEM to directly correlate, on the basis of real time in situ observations, surface morphology and local distribution of magnetization, has provided crucial insights into these SRT mechanisms.…”

Study of the island morphology at the early stages of Fe/Mo(110) MBE growth

“…Further in the text we will use notations E E 2 E 3 for interaction energies with first, second and third nearest neighbors correspondingly. Energies for the F on M system were calculated by Yang and Asta 1 employing spin-polarized electronic density functional theory, generalized-gradient approximation [6] calculations. Details of these calculations will be discussed in a future publication.…”

“…Iron films grown on molybdenum are known to have interesting ferromagnetic properties [1]. Hence, nature and formation of the iron islands at the early stages of molecular beam epitaxy (MBE) growth are attracting great amount of researchers' attention.…”

X-ray photoelectron emission microscopy in combination with x-ray magnetic circular dichroism investigation of size effects on field-induced Néel-cap reversal

“…11 These single-crystalline submicron-sized structures are obtained by epitaxial growth on a Mo(110) or W(110) buffer layer deposited on a (11-20) sapphire substrate at typically 500 °C and exhibit atomically flat facets [ Fig. 1(a)].…”