Growth Of Fe Films Research Articles

Scanning tunneling microscopy on the growth of Fe films on Cu(100)

We report on a scanning tunneling microscopy study of the condensation of Fe on Cu(100) at room temperature and the influence of subsequent annealing at 100°C and 230°C in the coverage range of 0.1–4 monolayers (ML), using an Fe flux of 1 ML/min. After nucleation of the Fe deposit in the form of small islands with single-layer height, the growth proceeds until after coalescence and smoothing of the island structure the growth continues in a layer-by-layer-like mode. In the submonolayer coverage range we found an Fe-induced diffusion of Cu atoms already for room temperature deposition leading to step roughening and formation of two-dimensional Cu islands, which prevent the formation of large two-dimensional Fe islands at low coverages. Annealing the films gives rise to considerable changes of the film morphology due to a large mass transport of Cu atoms.

Measurements of dynamic scaling from epitaxial growth front: Fe film on Fe(001).

Dynamic scaling behavior has been observed during the growth of Fe films on Fe(001) using high-resolution low-energy electron diffraction technique. The interface width grows with time according to the power law w∼t β , with β=0.22±0.02. Time-invariant self-affine behavior on the short-range scale has also been observed with the roughness exponent α=0.79±0.05. The time-invariant characteristic agrees with the recent prediction based on the dynamic scaling theory. From the measured growth exponents, we suggest that the growth of Fe film is more consistent with a conservative growth process

Study of the growth of Fe on Ru(0001) by low-energy electron diffraction

Abstract Qualitative and quantitative LEED (low-energy electron diffraction) and AES (Auger electron spectroscopy) studies of the growth of Fe films on Ru(0001) show that the growth mode is the Stranski-Krastanov mode: monolayer growth followed by island growth. The first monolayer of Fe is pseudomorphic with the hexagonal Ru(0001) net at an interlayer spacing of 2.05 A: the Fe atoms are in the sites dictated by continuation of the substrate's hexagonal close-packed (hcp) stacking. Thicker films consists of 3-dimensional bcc- Fe{ 100} domains in two equivalent Kurdjumov-Sachs orientations, rotationally related to one another by the 6-fold symmetry of the substrate net. These results do not support recent reports of the growth of hcp Fe on Ru(0001). Possible connections between the present structure results and the magnetic properties of Fe/Ru ultra-thin films reported by others are discussed.

Auger electron diffraction study of the growth of Fe(001) films on ZnSe(001)

The growth of Fe films on ZnSe(001) epilayers and bulk GaAs(001) substrates has been studied to determine the mode of film growth, the formation of the interface, and the structure of the overlayer at the 1–10 monolayer level. Auger electron diffraction (AED), x-ray photoelectron spectroscopy (XPS), and reflection high-energy electron diffraction data are obtained for incremental deposition of the Fe(001) overlayer. The coverage dependence of the AED forward scattering peaks reveals a predominantly layer-by-layer mode of film growth at 175 °C on ZnSe, while a more three-dimensional growth mode occurs on the oxide-desorbed GaAs(001) substrate. XPS studies of the semiconductor 3d levels indicate that the Fe/ZnSe interface is less reactive than the Fe/GaAs interface.

Ultrathin magnetic Fe films on W(001): A spin-polarized inverse photoemission study of Fe electronic structure evolution (abstract)

By using spin-dependent electron spectroscopic techniques, one can explore the relevant problems in 3d metallic ferromagnetism, including temperature effects. Current surface science methods of ultrathin-film preparation and characterization make it possible to study interesting two dimensional magnetic systems. In the present work, ultrathin epitaxially grown Fe films on W(001) have been investigated by spin- and angle-resolved inverse photoemission spectroscopy. The evolution of the electronic structure has been studied for thickness from one monolayer to ‘‘bulklike’’ Fe thin films. In-plane remanent magnetization is observed. In the thick bulklike sample, transitions to majority and minority states near the H point of bcc Fe were identified, in contrast with data from bulk Fe(001).1 The thinner Fe films showed a trend of ‘‘collapsing’’ d bands at H′25. The results suggested a reduced Curie temperature for monolayers thick films. Information obtained for examining the correlation length in the itinerant ferromagnetic systems does not support the local-band picture at finite temperatures.2

Substrate modified growth of epitaxial Fe films (abstract)

It is now clear that both the atomic and magnetic properties of epitaxial Fe films can be controlled by the precise nature of the substrate which acts as the template for the growth. We have investigated the role of defects and strain arising from lattice mismatch on the growth and the magnetic properties of the Fe films. The films were grown by molecular-beam epitaxy (MBE) on three different well characterized surfaces: GaAs(100), In0.2Ga0.8As(100), and Fe(100). The first two surfaces were also prepared by MBE. This mole fraction of In was chosen to match the lattice constant of bulk α-Fe. The growth of the Fe film was characterized by using reflection high-energy electron diffraction (RHEED) and the results indicate that the morphology of the Fe films is smoother on the InGaAs surface than on the GaAs surface. Yet is is still much rougher than the growth on Fe(100) substrate. The magnetic properties were measured by using a SQUID magnetometer and coercivity values are comparable to that of the films grown on ZnSe.1

MBE growth of single crystal α-Fe films on ZnSe (001) and (110)

We report the growth by molecular beam epitaxy oh high quality single crystal films of ferromagnetic α-Fe on ZnSe (001) and (110) epilayers grown on chemically etched and annealed GaAs wafers. The films were characterized by reflection high energy electron diffraction (RHEED), Auger electron spectroscopy (AES), X-ray diffraction (θ-2θ), ferromagnetic resonance (FMR) and vibrating sample magnetometry. RHEED demonstrates single crystal Fe film growth in registry with the ZnSe surface, and indicates that the surface order of the Fe (110) films is superior to that of the Fe (001) films. The FMR linewidth and measured coercive fields are significantly smaller than previously reported for similar Fe films grown directly on the GaAs substrates. Room temperature FMR spectra (35 GHz) of thin Fe (001) films (∼140 Å) exhibit symmetric Lorentzian lineshapes with a linewidth of 45 Oe, which represents the narrowest 35 GHz FMR linewidth ever measured in single crystal iron, and approaches the theoretical lower limit set by Landau-Lifschitz broadening.