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We have grown Fe films on an epitaxial Pd monolayer on Cu(001) single crystals at room temperature, both Fe and Pd by pulsed laser deposition. The presence of the Pd interlayer influences growth, structure, and magnetism of the Fe films. Up to the thickness of 1.6 ML the Fe films show an out-of-plane easy axis of magnetization which changes to in-plane above. A linear dependence of the longitudinal Kerr rotation on the Fe thickness is obtained despite existing structural transformations. A strong increase of the Curie temperature TC is observed for the Fe films on Pd/Cu(001) compared to the Fe films grown directly on Cu(001). A correlation of the magnetic properties with possible structural changes and the role of Pd monolayer is discussed. [ABSTRACT FROM AUTHOR]

The magnetization states of 20-nm-thick rectangular Co thin-film elements are studied with micromagnetic modeling and x-ray magnetic circular dichroism photoemission electron microscopy. The energies of ten domain configurations obtained in the modeling are compared with the frequency of occurrence of the corresponding virgin domain structures as a function of aspect ratio from 1:1 to 1:3 and of width from 200 to 600 nm. The results show that the abundance of the virgin states is largely determined by the magnetic energy densities of the elements. [ABSTRACT FROM AUTHOR]

Presents information on a study which demonstrated high-resolution imaging of domains and domain walls in the scanning electron microscope. Imaging of surface domains and domain walls; Discussion of stoner excitations in itinerant ferromagnets; Examination of spin-polarized photoemission from thin films.

The correlation between mechanical stress and magnetic anisotropy of Ni and Fe films on Cu(001) is investigated. The magnetoelastic coupling and the film stress during the growth are measured in situ with a highly sensitive optical bending beam technique. For Ni a dramatically reduced magnetoelastic coupling of B[sub 1]=3.5 MJ/m[sup 3] is found for films thinner than 10 ML, roughly one third of the bulk value of 9.4 MJ/m3. This change is explained by a strain correction to the magnetoelastic coupling. The influence of the interfaces does not significantly contribute to the magnetoelastic coupling. A very small magnetoelastic coupling of 0.4 MJ/m3 for Fe films in the range from 12 ML to 25 nm is attributed mainly to the crystallographic orientation of the bcc–Fe. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We report on a compact electron spin analyzer based on exchange scattering from a magnetic surface. The heart of the detector is an Fe(001) thin film grown on W(001) with chemisorbed oxygen in the p(1×1) structure. The device is mounted at the exit of an energy dispersive analyzer and works at a scattering energy of about 13.5 eV. Its figure of merit is 2×10-3, combined with an excellent stability of more than 2 weeks in UHV. [ABSTRACT FROM AUTHOR]

We report on the dynamics of magnetic domain structure conversions exhibited by soft magnetic thin-film elements of elementary geometrical shape (square, disc, triangle) when exposed to a strong external magnetic field. Starting from flux closure vortex patterns, the magnetic structures evolve towards an in-plane saturated state under the influence of an external field. This irreversible and nucleation-free magnetization process occurs on the time scale of picoseconds. The details of this conversion are investigated by means of a time-resolved micromagnetic finite element modeling. We find a sensitive dependence of the temporal evolution of the magnetic structure on the value of the damping parameter in Gilbert''s equation of motion. In the case of high damping, domain wall motion dominates the process, while lower damping leads to the formation of a 360° wall which collapses by emitting magnetization waves. It is shown that the mobility of vortices is generally much lower than that of domain walls. The calculations indicate that at a low damping, a magnetic vortex can act almost as a source for concentric waves in ferromagnetic thin-film elements. [Copyright &y& Elsevier]

We report on Fe films grown on Au-buffered Si(001) showing perpendicular magnetization at ambient temperatures. The in-plane magnetization in ultra-thin Fe films grown at 150 K reorients irreversibly out-of-plane as a result of annealing close to room temperature. A Au cap layer which is expected to segregate to the top of the Fe film may be responsible for this behaviour. This hypothesis is based on the observation of an in-plane to out-of-plane reorientation of magnetization upon the growth of an ultra-thin Au cap layer on a slightly thicker Fe film. The origin of such a strong out-of-plane anisotropy of Fe induced by Au is discussed. [ABSTRACT FROM AUTHOR]

The understanding and control of anisotropy in Fe films grown on cubic systems such as GaAs and MgO has been of interest from the point of view of applications in devices. We report magnetic anisotropy studies on Fe/GaAs(001) and Fe/MgO/GaAs(001) prepared by pulsed laser deposition. In Fe/GaAs(001), magneto optical Kerr effect (MOKE) measurements revealed a dominant uniaxial anisotropy for Fe thickness less than 20 monolayers (ML) and this was confirmed by ferromagnetic resonance (FMR) studies. Multiple steps in the hysteresis loops were observed for Fe films of thickness 20 and 25 ML. Whereas, in Fe/MgO/GaAs(001), even at 25 ML of Fe, the uniaxial anisotropy remained dominant. The anisotropy constants obtained from FMR spectra have shown that the relative strength of uniaxial anisotropy is higher as compared to the cubic anisotropy constant in the case of Fe/MgO/GaAs(001). [ABSTRACT FROM AUTHOR]

Reports that cobalt/copper(111) [Co/Cu(111)] films can be grown with good layer-by-layer morphology and less stacking faults by pulsed laser deposition. Achievement of complete antiferromagnetic coupling; Growth resulting from the thermal deposition of Co unto Cu; Mechanism of the improvement towards layer-by-layer growth in ultrathin metallic films.

Describes a Kerr microscope designed for in situ investigation of magnetic ultrathin films in ultrahigh vacuum environment. System's permission of quick visualization of domain patterns with a specific lateral resolution; Possibility of simultaneous optical magnetometry.

In the search for a correlation between the magnetism and the microstructure of ultrathin films, straightforward layer-by-layer growth is desirable. The thermal deposition of Fe onto Cu(111), however, does not result in this growth mode. In this letter, we compare the initial growth of Fe on Cu(111) prepared by pulsed laser deposition (PLD) with thermally deposited Fe/Cu(111) using scanning tunneling microscopy (STM). In PLD, from the beginning there is two-dimensional nucleation and growth, in contrast to the initial bilayer nucleation and growth found for thermal deposition. Therefore, it is shown by STM that PLD grown films exhibit greatly improved layer-by-layer growth. The different experimental results are interpreted in terms of the very high deposition rate during PLD. © 1996 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Analyzes the consequences of the thickness dependence of anisotropy in ultrathin films for the spin-reorientation transitions (SRT) behavior in applied field for the two major field configurations. Occurrence of spontaneous SRT; Specification to ultrathin films.

Presents a study which investigated the magnetic anisotropy of Iron (Fe) or nickel (Ni) ultrathin films. Methodology of the study; Experimental results; Theoretical interpretation; Conclusions.

Presents an abstract of the study 'Magnetism and Structure of Ultrathin fcc Fe[subx]Co[sub1-x] films on Cu(001),' by A. Dittschar, M. Zharnikov, W. Kuch, C.M. Schneider and J. Kirschner.

Demonstrates an easy implementation of the cantilever bending beam approach to measure stress during film growth in ultrahigh vacuum. Use of a simple and compact optical deflection technique; Detection of film stress with sub-monolayer sensitivity.

We apply the cantilever deflection technique to measure stress in nm thin BaTiO 3 and SrTiO 3 films during pulsed laser deposition on a Pt(0 0 1) single crystal cantilever substrate. We find a compressive film stress of −4.2 GPa for BaTiO 3 on Pt(0 0 1) (misfit = −2.3%), whereas the deposition of SrTiO 3 (misfit = +0.4%) induces a tensile stress of +1.5 GPa. The stress measurements are augmented by in situ low energy electron diffraction experiments which indicate an epitaxial order of the films. We apply continuum elasticity to calculate film stress. We conclude that sign and magnitude of the measured stress are due to the epitaxial misfit between film and substrate, which is −2.3% and +0.4% for BaTiO 3 and SrTiO 3 , respectively. We identify that in addition to misfit also the oxygen partial pressure during PLD film growth influences film stress. PLD growth in an oxygen-free environment leads to factor of two increased tensile stress in SrTiO 3 on Pt(0 0 1) as compared to growth at p O 2 = 10 − 4 mbar. The role of film stoichiometry for film stress is discussed. [ABSTRACT FROM AUTHOR]

Thermal deposition (TD) and pulsed laser deposition (PLD) techniques were used to prepare GaAs/Fe(001) crystalline ultrathin films. The magnetic environment of Fe at the Fe/GaAs(001) interface was investigated by means of conversion electron Mössbauer spectroscopy using an 57Fe probe layer having the equivalent thickness of two atomic layers. The magnetic anisotropies were measured using ferromagnetic resonance. PLD samples were affected by an appreciably higher degree of interface alloying compared with the TD films. The interface in-plane fourfold (cubic) anisotropy is significantly increased and the in-plane interface uniaxial anisotropy is significantly decreased in the PLD samples compared to those prepared using TD. The effective perpendicular demagnetizing field in the PLD films is significantly decreased compared to the TD samples due to an unexpected increase in the interface uniaxial perpendicular anisotropy at the Fe/Au(001) interface. [ABSTRACT FROM AUTHOR]

The proximity effect describes the extension of superconductivity into a metal, which is in contact with a superconductor. Scanning tunneling spectroscopy is used to probe this effect in a two-atomic-layer Pb/Ag nonsuperconducting film, surrounding a superconducting Pb nanoisland, with sub-nm spatial resolution. Here we show a nontrivial dependence of the length scales of the superconducting proximity effect on magnetic field. Surprisingly, we find that the magnetic field does not affect the induced superconductivity up to 0.3 T, but a breakdown of the proximity effect is induced for fields around 0.6 T, with a 1/Hp dependence with p ≅ 7. The unexpected robustness of the induced superconductivity in the presence of magnetic fields is ascribed to the high electronic diffusivity in the metallic wetting layer [ABSTRACT FROM AUTHOR]

Abstract: So-called split hysteresis loops have been measured for ultrathin ferromagnetic films grown on stepped surfaces. Since the shape of the loops is sensitive to the direction in which the magnetic field is applied with respect to the steps, the sample orientation against the field is particularly important. We performed systematic magneto-optical Kerr effect studies for 15 and 58ML of Fe grown on Au(1,1,13). In view of the complex magnetic anisotropy of such systems we discuss representative hysteresis loops taken at sample orientations misaligned from the field (and laser beam) direction. In particular, the presence of a so-called low field component to the hysteresis loops is discussed and its reversed polarity is explained. [Copyright &y& Elsevier]

Abstract: We report on the growth of thin Co films on Pd(111) at three different temperatures 180K, 300K, and 550K. The structure and morphology was determined by scanning tunneling microscopy and low energy electron diffraction. The growth mode was found to vary with temperature. For 180K and 300K, we observed a tendency to double layer growth for the initial layers while at elevated temperatures, the initial film grows in single layer. For most conditions, non-ideal three-dimensional growth was observed. Two-dimensional growth was only found for growth temperature of 550K and coverages above 5ML. Depending on temperature, the Co islands at low coverages exhibit three principally different shapes: dendritic at 180K, hexagonal at 300K and triangular at 550K. For growth at 550K and coverages above 5ML, the islands changed to an irregular shape. This transition is most likely responsible for the transition to 2D growth. Further, the large strain is relaxed by the creation of a dislocation network with mixed fcc and hcp stacking. Depending on the temperature and coverage, a hexagonal or a triangular network was observed. Finally, we have investigated the effect of annealing Co films prepared at 180K and 300K. Heating to 490K leads to coarsening and intermixing. [Copyright &y& Elsevier]

Abstract: The magnetization reversal of the magnetically soft permalloy layer in a spin-valve-like FeNi/Cu/Co trilayer was studied using photoelectron emission microscopy combined with X-ray magnetic circular dichroism, which allows to image the magnetic domain structure in an element-selective way. Nanosecond-short magnetic field pulses with amplitudes between 3.3 and 16.3mT were applied one by one to reverse the magnetization of the FeNi layer. Images of the magnetic domain structure were taken after application of each pulse, and the mobility of magnetic domain wall motion in the FeNi layer was deduced. The reversal mechanism of the FeNi layer was found to depend on the applied pulse length, amplitude, and on the energy and direction of the coupling between the two ferromagnetic layers. [Copyright &y& Elsevier]

Spin-polarized electron energy loss spectroscopy (SPEELS) is a unique tool to determine the spin-wave dispersion of ultrathin films and surfaces over the whole Brillouin zone. Ultrathin Co films on Cu(001) show well-defined spin-wave loss peaks in the SPEEL spectra. For 3 ML Fe films on 1 ML Co/Cu(001) the spin-wave peaks are much broader compared to the Co case but show dispersion. In 5-ML-thick bcc Fe films on W(110), a very broad feature assigned to spin-wave excitation was observed as well, which, however, does not show significant dispersion in the investigated range of large wavevectors. [Copyright &y& Elsevier]

We report on the magnetic and structural characterization of Au/(Ni)Fe/MgO/Fe magneto-tunnel junctions grown on InP(0 0 1) and GaAs(0 0 1). On GaAs substrates almost perfect single crystal junctions with sharp interfaces were achieved as seen by low energy electron diffraction and transmission electron microscopy. In situ magnetization loops obtained with the longitudinal magneto-optic Kerr effect show an independent switching of magnetization of both Fe layers suggesting that the two Fe layers are magnetically decoupled by the MgO layer. [Copyright &y& Elsevier]

In order to test the presence of interatomic multi-atom resonant photoemission (MARPE) in 3d magnetic ultrathin films, 2p photoelectron emission of various ferromagnetic 3d metals was studied while the excitation energy was tuned around the L2,3 core level absorption edge of a different 3d metal. Both elements were in direct contact either as bilayer or as alloys to maximize this possible effect. Systems under study were Fe/Co, Fe/Ni, Fe30Ni70, Co, Co90Mn10, and Ni90Mn10, all grown as epitaxial films on Cu(001). No measurable change in intensity of the 2p photoemission intensities in normal emission for 45° incidence of more than 2.5–5% was found as a result of resonant excitation of neighboring atoms in any of these systems. We can thus exclude the presence of significant MARPE in these metallic systems in the present experimental geometry. This is further confirmed by the photon energy dependence of the linear magnetic dichroism in the Fe 2p photoemission of a Fe/Co film, which is not influenced by Co L2,3 edge resonant absorption. [Copyright &y& Elsevier]