Fe Film Thickness Research Articles

Signatures of magnetism control by flow of angular momentum

Exploring new strategies to manipulate the order parameter of magnetic materials by electrical means is of great importance not only for advancing our understanding of fundamental magnetism but also for unlocking potential applications. A well-established concept uses gate voltages to control magnetic properties by modulating the carrier population in a capacitor structure1–5. Here we show that, in Pt/Al/Fe/GaAs(001) multilayers, the application of an in-plane charge current in Pt leads to a shift in the ferromagnetic resonance field depending on the microwave frequency when the Fe film is sufficiently thin. The experimental observation is interpreted as a current-induced modification of the magnetocrystalline anisotropy ΔHA of Fe. We show that (1) ΔHA decreases with increasing Fe film thickness and is connected to the damping-like torque; and (2) ΔHA depends not only on the polarity of charge current but also on the magnetization direction, that is, ΔHA has an opposite sign when the magnetization direction is reversed. The symmetry of the modification is consistent with a current-induced spin6–8 and/or orbit9–13 accumulation, which, respectively, act on the spin and/or orbit component of the magnetization. In this study, as Pt is regarded as a typical spin current source6,14, the spin current can play a dominant part. The control of magnetism by a spin current results from the modified exchange splitting of the majority and minority spin bands, providing functionality that was previously unknown and could be useful in advanced spintronic devices.

Effect of electrical stress on time dependent dielectric breakdown (TDDB) tolerate capability of HfO2–ZrO2 ferroelectric films with different thicknesses

HfO2-based ferroelectric materials as the most promising candidate for the ferroelectric memories, have been widely studied for more than a decade due to their excellent ferroelectric properties and CMOS compatibility. In order to realize its industrialization as soon as possible, researchers have been devoted to improving the reliability performance, such as wake up, imprint, limited endurance, et al. Among them, the breakdown characteristic is one of main failure mechanisms of HfO2-based ferroelectric devices, which limits the write/read reliability of the devices. Based on this, we systematically studied the effect of thickness on the time-dependent dielectric breakdown (TDDB) tolerate capability of HfO2–ZrO2 (HZO) FE films under both forward and reverse electrical stress conditions. The thickness of HZO FE film ranged from 6 to 20 nm. Our findings reveal that decreasing the thickness of the HZO FE film leads to an improvement in TDDB tolerance capability which is attributed to the fact that higher density of oxygen vacancies in thinner HZO FE films can effectively inhibit the generation of new oxygen vacancies and the growth of conductive filaments, thus effectively improving the TDDB characteristics. These results provide a potential solution for mitigating breakdown characteristics of HfO2-based ferroelectric devices in memory applications.

Monitoring Reinforced Concrete Structures Using Iron Thin Film Coated Optical Fibre Sensors

Structural health monitoring (SHM) of reinforced concrete structures (RCS) is crucial for mitigating the consequences of their deterioration. By identifying and addressing the issues early, SHM helps reduce environmental impact, safeguard lives, and enhance economic resilience. Rebar corrosion is a leading cause of early RCS decay and optical fibre sensors (OFS) have been employed for its monitoring. Reflection optrodes using optical fibres where the tip is coated with iron (Fe) thin films offer a robust, longlasting and straightforward solution. This study investigates the tracking of spectral changes during the Fe thin film corrosion, which has been neglected in the literature, in favour of tracking reflection changes from thin film spalling. A multimode fibre tip, coated with a thin Fe layer embedded in concrete, allows spectral changes to be observed during corrosion. A 100 nm thick Fe film was deposited using radio frequency magnetron sputtering on polished fibre tips. Corrosion was induced by applying salted water drops and allowing the fibre tip to dry. Corrosion monitoring was successful for both air-exposed and cementembedded tips, with results compared to reflection simulations of Fe, Fe2O3, and Fe3O4 thin films. This study supports monitoring at different wavelengths, enhancing robustness, cost-effectiveness and earlier detection.

(Invited) Formation and Characterization of Fe-Silicide Nanodots for Optoelectronic Application

Light emission from group-IV based nanostructures has been attracting much attention in the field of Si-based photonics because of its potential to combine photonic processing with electronic processing on a single chip [1]. Among various Fe-silicides, semiconducting β-FeSi2 shows light emission in the near-infrared region [2, 3] and is one of promising materials in optoelectronic application from viewpoints of tuning emission energy and improving luminous efficiency by means of quantized structures. In this work, we focus on low temperature formation of β-FeSi2 nanodots (NDs) over ~1011 cm-2 in areal density on SiO2 and the characterization of light emission properties of β–FeSi2 NDs.After conventional wet-chemical cleaning steps of p-type Si(100) substrates, a ~300-nm-thick SiO2 layer was grown at 1000°C in dry O2 and followed by dipping shortly in a dilute HF solution to make uniform surface termination with Si-OH bonds. After that, Fe films in the thickness range from 1.0 to 3.0 nm were formed on the OH-terminate SiO2 layer by electron beam evaporation without any extra heating. And then, the Fe–films were exposed to remote plasma of pure H2 (H2-RP) at 400°C to form highly-dense Fe-NDs [4]. Subsequently, so-prepared Fe-NDs were exposed to pure SiH4 at 400°C while controlling the amount of SiH4 exposure by duration and pressure.AFM images taken after exposure of Fe-films to H2-RP confirm the high-density formation of well-defined NDs. In the cases of H2-RP exposure of 1.3-nm-thick and 3.0-nm-thick Fe-films, the areal dot densities as high as ~1.1 × 1011 and ~1.3 × 1011 cm−2 were obtained, respectively, in which the average dot-heights of self-assembled Fe-NDs were determined to be ~5.3 and ~10.9 nm, respectively, by fitting a log-normal function to each measured size distribution. Notice that AFM images taken after SiH4 exposure show almost no change in the areal dot density while a slight increase in the average dot height. From cross-sectional transmission electron microscope images, we have also verified the formation of distorted-spherical shape NDs with a lattice spacing of ~0.18 nm associated with β-FeSi2. And the result is well consistent with the chemical composition of NDs after SiH4 exposure as evaluated by x-ray photoelectron spectroscopy. In addition, with 976 nm light excitation using a semiconductor laser, the NDs after the SiH4 exposure show stable photoluminescence (PL) signals in the energy region from ~0.7 to ~0.9 eV even at room temperature. On the other hand, no PL signals were detected from the NDs before the SiH4 exposure and after Ar anneal at 400°C. Also, when the size of the Fe-silicide NDs was increased from ~5.3 to ~10.9 nm in average dot height by increasing the initial Fe-film thickness, a distinct red-shift in PL was clearly observed. Thus, the observed PL can be interpreted in terms of radiative recombination of photogenerated carriers through quantized states of β-FeSi2 NDs. These results indicate that SiH4 exposure to Fe-NDs formed on SiO2 is a very promising technique for the low-temperature fabrication of luminescent FeSi2 NDs.AcknowledgementThis work was supported in part by Grant-in-Aid for Scientific Research (A) 21H04559 of MEXT Japan, and the Cooperative Research Project Program of the Research Institute of Electrical Communication, Tohoku University.

(Invited) Formation and Characterization of Fe-Silicide Nanodots for Optoelectronic Application

We have demonstrated the formation of high areal-density β-FeSi2nanodots (NDs) on SiO2 by remote H2-plasma induced self-assembly of Fe-NDs and subsequent SiH4-exposure at 400°C. Under either 976- or 514.5-nm light excitation of NDs after the SiH4-exposure, stable photoluminescence (PL) signals, being characteristic of the semiconducting phase as β-FeSi2, were observed even at room temperature in the energy region over the indirect bandgap of bulk β-FeSi2 (~0.7 eV). The temperature dependence of PL was confirmed to be weak significantly in comparison to that of bulk bandgap, implying light emission from tightly confined NDs. And also, with a decrease in the average dot size by controlling the initial Fe-film thickness, a clear blue shift in PL was observed. The results are associated with quantum size effect in radiative recombination of photoexcited electron-hole pairs.

Electrically excited magnetoelastic waves and magnetoacoustic resonance in ferromagnetic films with voltage-controlled magnetic anisotropy

Ferromagnet-dielectric heterostructures may possess interfacial magnetic anisotropy, which varies with the electric field created in the dielectric interlayer. Such a voltage-controlled magnetic anisotropy (VCMA) represents an efficient tool for the excitation of spin waves without the use of microwave magnetic fields. In ferromagnets with a significant magnetoelastic coupling between spins and strains, however, the magnetization precession in the spin wave induces elastic vibrations. Here we report micromagnetoelastic simulations of the coupled spin and acoustic dynamics generated in the thick Fe film brought into contact with an MgO nanolayer subjected to a microwave voltage. It is found that the electrically induced periodic modulation of VCMA gives rise to the excitation of both spin and elastic waves in the magnetostrictive Fe film. Remarkably, the magnetoelastic coupling makes it possible to generate propagating spin waves having frequencies well below the ferromagnetic resonance frequency. Furthermore, when the voltage frequency approaches a value ${\ensuremath{\nu}}^{*}$ at which the dispersion relations of pure spin and transverse elastic waves cross, the excitation of traveling magnetoelastic waves with a specific hybrid dispersion occurs in the Fe film. To explain the variety of observed phenomena, we propose a generalized dispersion relation for magnetoelastic waves, which accounts for a possible difference between the wave numbers of their magnetic and elastic components. The analysis of the simulation data also reveals that frequency dependencies of the amplitudes of magnetic oscillations and elastic vibrations display significant anomalies around the crossing-point frequency ${\ensuremath{\nu}}^{*}$, which originate from the electrically induced magnetoacoustic resonance.

Ultrafast electron dynamics in Au/Fe/MgO(001) analyzed by Au- and Fe-selective pumping in time-resolved two-photon photoemission spectroscopy: Separation of excitations in adjacent metallic layers

The transport of optically excited, hot electrons in heterostructures is analyzed by femtosecond, time-resolved two-photon photoelectron emission spectroscopy (2PPE) for epitaxial Au/Fe/MgO(001). We compare the temporal evolution of the 2PPE intensity upon optically pumping Fe or Au, while the probing occurs on the Au surface. In the case of Fe-side pumping, assuming independent relaxation in the Fe and Au layers, we determine the hot electron relaxation times in these individual layers by an analysis of the Au layer thickness dependence of the observed, effective electron lifetimes in the heterostructure. We show in addition that such a systematic analysis fails for the case of Au-side pumping due to the spatially distributed optical excitation density, which varies with the Au layer thickness. This work extends a previous study [Beyazit et al., Phys. Rev. Lett. 125, 076803 (2020)] by new data leading to reduced error bars in the determined lifetimes and by a non-linear term in the Au-thickness dependent data analysis which contributes for similar Fe and Au film thicknesses.

Evolution of superconductivity dependence on substrate temperature with thickness of Fe(Se,Te) coated conductors deposited on metal tapes

Fe(Se,Te) films of different thicknesses were deposited on metal tapes by pulsed laser deposition at different substrate temperatures. It is found that the substrate temperature dependence of superconductivity changes with the Fe(Se,Te) film thickness. When fabricating thin Fe(Se,Te) films with a thickness of about 150 nm, moderate substrate temperatures are conducive to balancing the influence of texture and stoichiometry on superconductivity, contributing to the obtainment of good superconductivity. When the Fe(Se,Te) films’ thickness is about 300 nm, the optimal substrate temperatures are lowered due to the determination of film superconductivity by the inhomogeneity of longitudinal chalcogen distribution via the cooperation of Te loss in the long-term-ablated target and the attraction of metal ions in the buffer layer. In addition, with a further increase in thickness from 300 to 600 nm, the self-field critical current of thick Fe(Se,Te) films continuously increases, but the critical current density increases first and then decreases, which is thought to be a result of the misoriented grains or non-superconducting phase due to the large deviation between the actual deposition temperature and the set substrate temperature, and the Se excess in the film. In addition, the 450-nm-thick Fe(Se,Te) film exhibits excellent self-field and in-field performances at 4.2 K: 1.308 MA/cm2 at self-field and over 0.5 MA/cm2 at 9 T. Point pinning, which is the local lattice disturbance randomly distributed in the film observed by transmission electron microscopy, dominates over the entire temperature range.

Observation of magnetoconductivity with terahertz probes for ferromagnetic Fe films

Ultrafast characterization of spin-dependent transport behavior in ferromagnetic systems without contact probes has been of strong demand, recently. We have experimentally investigated spin-dependent complex conductivity for ferromagnetic Fe films of various thickness by means of terahertz time-domain transmission spectroscopy. Comparison of the transmitted terahertz wave amplitude and the spin-dependent conductivity reveals that the magnetization state of films effectively determines the complex conductivity. Non-invasive observation of spin-dependent conductivity by contact-free terahertz probe method is proven to be promising in further investigating spintronic materials, particularly on an ultrafast timescale.

Magnetic state instability of disordered electrodeposited nanogranular Fe films

The magnetic properties of Fe are exploited in variety of different nanotechnological applications. The electrodeposition conditions have strong influence on resulting properties of Fe films. In this study different methods were used to identify and characterise the morphology and the magnetic properties of Fe films of various thickness electrodeposited at different temperatures. The studied electrodeposited Fe films had elongated structural components orientated mostly perpendicularly to the surface, which caused the magnetisation tilt from the surface of the film. The electrodeposition at 20°C led to more fine and disordered structure compared to the structure obtained at higher electrodeposition temperature, i.e. 65°C. . By applying magnetic field perpendicular to the surface, the minor hysteresis loops of the sample electrodeposited at 20°C changed significantly with repeated measurements. The loop shape depended on initial conditions, probably on the variable magnetic state left after previous magnetisation or on the changes in sample position caused by small angle differences. The analysis of first order reversal curves showed that the magnetisation switching field (pseudo-coercivity) depended on magnetisation at reversal magnetic field, considerably only for 20°C thin film. The magnetic peculiarities of thin film grown at 20°C can be explained by the competing influence of the dipolar interactions and shape anisotropy of vertically elongated grains, and the presence of intergranular soft magnetic material.

The Effects of Fe Film Thickness and the H₂ Annealing Time on the Spin-Capability of Carbon Nanotube Forest with Chemical Vapor Deposition Method.

The effects of as-deposited iron (Fe) film thickness and the hydrogen (H₂) annealing time on the spin-capability of carbon nanotube (CNT) forest have been studied. Both, the as-deposited Fe film thickness and the H₂ annealing time significantly changed the morphology of Fe nanoparticles (NPs) after annealing process during the synthesis step of spin-capable carbon nanotube (SCNT) forest. The spin capability of CNT forests depended heavily on the different thicknesses of Fe films and the H₂ annealing time. In conclusion, the spin-capability of CNT forest can be achieved by controlling the initial Fe film thickness and/or the H₂ annealing time.

Growth behavior, physical structure, and magnetic properties of iron deposited on Tris(8-hydroxy quinoline)-aluminum

Growth behavior and evolution of magnetism as a function of Fe thin film thickness onto organic semiconductor tris(8-hydroxyquinoline)-aluminum, (Alq3) thin film was investigated in-situ using electrical resistance and magneto-optic Kerr effect (MOKE) measurements, respectively. The variation of electrical resistance with Fe film thickness reveals the Volmer-Weber growth of Fe on Alq3 film. Reflection high energy electron diffraction (RHEED) pattern resembles polycrystalline BCC structure of Fe. Ex-situ x-ray reflectivity (XRR) measurement from the Fe/Alq3/Si sample reveals that Fe diffuses into Alq3 to form an alloy layer of 50 Å thickness with Fe volume fraction of 0.4. In-situ MOKE study affirms anomalous magnetic behavior at the initial stage of Fe growth. Initially hysteresis loop appears and develops in a particular direction, and then vanishes at certain thickness. With further growth of Fe hysteresis loop appears again and grows in the opposite direction. The observed unusual changes in magnetic behavior as a function of Fe thickness may be explained in terms of the contribution from the magnetic Fe-Alq3 alloy present in the intermix layer, the metallic Fe on top of Alq3 layer, and their antiferromagnetic coupling.

Modulation of PSSW resonance field affected by exchange stiffness A in Fe/NiFe/Fe multi-layer films with different Fe film thicknesses

Microwave devices, designed by the electromagnetic characteristics of spin waves, are widely used in radio frequency circuits and microwave systems, such as magnetic tunable filters, frequency multiplier, and signal-to-noise ratio enhancers. In order to manufacture these devices, it is not only the saturation magnetization (4πMs) and ferromagnetic resonance linewidth (ΔH) that need to be regulated, but also the exchange stiffness (A). In this study, the Fe (t nm)/Ni81Fe19 (50 nm)/Fe (t nm) multilayer films were proposed to regulate the 4πMs, ΔH, and A, which were fabricated using electron beam evaporation, and the dynamic magnetic properties of the film were studied by ferromagnetic resonance (FMR) spectroscopy. Firstly, we obtain the 4πMs, γ and Ha by fitting the uniform FMR mode. Then we obtain the exchange stiffness by fitting the first (p = 1) perpendicular standing spin wave (PSSW) mode. With the increasing Fe film thickness, the calculated saturation magnetization increased from 9250 to 14060Gs, FMR linewidth increased from 111.5 to 140.3Oe and the exchange stiffness decreased from 22.1 × 10−12 to 7.8 × 10−12J/m.

A self‐consistent multiple‐peak structure of the photoemission spectra of metallic Fe 2p as a function of film thickness

The Fe 2p spectrum has a very complex peak structure and a very strong background. Based on the comparison of the spectra for iron film with varying thicknesses, an experimental multiple‐peak structure for the metallic Fe 2p spectrum is proposed. The analysis required the use of state‐of‐the‐art background modeling (including the active approach) and peak‐fitting methods (including the simultaneous fitting method). A key aspect that allowed for this analysis is that the peak components are the same for various Fe film thicknesses, but with varying relative intensities. The early stages of oxidation are analyzed. The angular dependence of the peak components is also discussed.

Periodic Coulomb blockade oscillations observed in single-layered Fe nanodot array

Clear Coulomb blockade characteristics of Fe nanodots in a multiple-nanodot array were achieved. The array was fabricated in a self-assembled manner by Fe deposition between the source and drain electrodes on thermally-grown SiO2/Si substrates. Current oscillations as a function of gate voltage were observed in almost all the devices having an average Fe film thickness (1.8–2.8 nm) less than the threshold thickness showing metallic conduction. The oscillations in major cases were complex owing to contributions from many dots; periodic current oscillations, apparently arising from a single dot, were seen with a certain probability (approximately 10%) at the Fe film thickness range from 2.4 to 2.8 nm which was close to the thickness showing metallic conduction. The periodic oscillations were analyzed by considering the Fermi–Dirac distribution function and this simple oscillation appeared from a certain single dot that existed among many other dots contributing to the background current. The phase of the oscillation period occasionally shifted. This phenomenon is explained by a single-electron charging effect from another dot far away from the single dot under consideration.

Anomalous Hall magnetoresistance in single-crystal Fe(001) films

The angular-dependent magnetoresistance (MR) in epitaxial Fe(001) films grown on MgO(001) is systematically investigated at room temperature. The resistivities with in-plane magnetic fields parallel (ρx) and transverse (ρy) to a current and a perpendicular field (ρz) show a correlation of ρz ≈ ρx > ρy for Fe film thickness (dFe) between 3 and 50 nm, which is distinctly different from the conventional anisotropic MR relation of ρx > ρy ≈ ρz. The dependence of such unusual MR on dFe is quantitatively explained by the competition between the anomalous Hall MR, intrinsic anisotropic MR, and the MR induced by the geometrical size effect in Fe films. Our results also reveal the strong four-fold symmetric terms in the measured angular-dependent MR with a linear dependence of 1/dFe.

Discussion of strong pinning effect via nonuniform PSSW mode in Fe/NiFe/Fe multi-layer films with different Fe film thicknesses

Multilayer films with high saturation magnetization and low ferromagnetic resonance linewidth have great potential for various applications in the era of high frequency and miniaturization. In this study, Fe (t nm)/Ni81Fe19 (50 nm)/Fe (t nm) multilayer films were fabricated using electron beam evaporation, and the microstructure, saturation magnetization, coercivity, ferromagnetic resonance (FMR) linewidth and perpendicular standing spin-wave (PSSW) mode are discussed in detail. With increasing Fe film thickness, the saturation magnetization of the multilayer films increased from 10,547 to 14,494 Gs, becoming closer to the theoretical value, and the ferromagnetic resonance linewidth showed an overall increasing trend. It is worth noting that a strong pinning effect has been found via the appearance of the PSSW mode in the FMR spectrum, when the thickness of Fe reaches 4 nm. As the thickness of the Fe film increased from 4 to 15 nm, the perpendicular standing spin-wave field (Hp) increased from 133 to 379 Oe, and the perpendicular standing spin-wave linewidth (ΔHp) increased from 68 to 148 Oe. Remarkably, with 8 nm thick Fe film, the multilayer films achieved excellent comprehensive performances with high saturation magnetization (4πMs, 13,525 Gs), a low in-plane ferromagnetic resonance field (Hr, 725 Oe), and a low FMR linewidth (ΔH, 84.24 Oe).

Electronic structures of MgO/Fe interfaces with perpendicular magnetization revealed by hard X-ray photoemission with an applied magnetic field

ABSTRACT We have developed hard X-ray photoelectron spectroscopy (HAXPES) under an applied magnetic field of 1 kOe to study the electronic and magnetic states related to the MgO/Fe interface-induced perpendicular magnetic anisotropy (PMA). In this work, we used MgO (2 nm)/Fe (1.5 and 20 nm)/MgO(001) structures to reveal the interface-induced electronic states of the Fe film. Perpendicular magnetization of the 1.5-nm-thick Fe film without extrinsic oxidation of the Fe film was detected by the Fe 2p core-level magnetic circular dichroism (MCD) in HAXPES under a magnetic field, and easy magnetization axis perpendicular to the film plane was confirmed by ex situ magnetic hysteresis measurements. The valence-band HAXPES spectrum of the 1.5-nm-thick Fe film revealed that the Fe 3d electronic states were strongly modified from the thick Fe film and a reference bulk Fe sample due to the lifting of degeneracy in the Fe 3d states near the MgO/Fe interface. We found that the tetragonal distortion of the Fe film by the MgO substrate also contributes to the lifting of degeneracy in the Fe 3d states and PMA, as well as the Fe 3d-O 2p hybridization at the MgO/Fe interface, by comparing the valence-band spectrum with density functional theory calculations for MgO/Fe multilayer structures. Thus, we can conclude that the Fe 3d-O 2p hybridization and tetragonal distortion of the Fe film play important roles in PMA at the MgO/Fe interface. HAXPES with in situ magnetization thus represents a powerful new method for studying spintronic structures.

Fabrication and characterization of microwave phase shifter in microstrip geometry with Fe film as the frequency tuning element

Abstract A series of ultra-small planar broad-band phase shifters with wide range of phase shift are designed and tested in this investigation. To achieve this performance a series of microstrip transmission lines with Iron (Fe) films of various thicknesses (from 100 to 800 nm) were designed, fabricated and tested. The basic principle of operation of these phase shifters are based on ferromagnetic resonance (FMR). The influence of the thickness of the magnetic layer was studied for two frequency regions: below and above the ferromagnetic resonance. This is because for a real-device the insertion loss should be less than −3 dB (or as low as possible). In the high frequency region, the optimal frequency (corresponding to the highest change in phase shift) increased significantly with the increase of the Fe film thickness (from 27 GHz for the structure with 100 nm of Fe to 43 GHz for the structure with 800 nm of Fe film). In the low frequency region, however, the optimal frequency varied little with the Fe layer thickness. The highest change in phase shift (~90 deg/cm) corresponded to the structure with the thinnest Fe layer for the low frequency region and with the thickest Fe layer for the high frequency region. In the high frequency region the Figure-of-Merit was about 20 deg/dB at low magnetic fields (

Fine-tuning of canted magnetization in stepped Fe films through thickness variation, Au capping, and quantum confinement

Author(s): Daobrowski, M; Cinal, M; Schmid, AK; Kirschner, J; Przybylski, M | Abstract: We present a joint experimental and theoretical study that demonstrates how to efficiently control a canted state of magnetization in Fe films grown on Ag(001) vicinal surface and precisely characterize it with the magneto-optical Kerr effect. It is shown that by employing different mechanisms to tune the magnetization tilting angle, any magnetization orientation within the plane perpendicular to the step edges can be achieved. In particular, increasing the Fe film thickness leads to continuous rotation of the magnetization easy axis toward the film surface and the sense of this rotation in uncovered films is opposite to that in films covered with Au. Another tuning mechanism is provided by oscillatory changes of the tilting angle at low temperatures due to formation of quantum well states in Fe films. The observed canting of magnetization is explained within a phenomenological model by an interplay of the shape anisotropy and two magnetocrystalline anisotropy terms, perpendicular and step-induced anisotropies, which results in an effective uniaxial magnetic anisotropy. The fitted thickness dependencies of the anisotropy constants accurately reproduce experimental variations of the tilting angle with both Fe and Au thicknesses as well as transient changes of the magnetization orientation in ultrathin Fe films upon submonolayer Au coverage, observed with spin-polarized low-energy electron microscopy.