Magnetic dichroism has been observed in the angular distribution of p-core level photoemission spectra excited from crystalline ferromagnets by unpolarized X-rays. The angular dependence of the angular and energy-resolved photoemission intensity was recorded as a function of the emission direction with respect to the crystal, revealing a strong variation of the magnetic dichroism with emission angle due to photoelectron diffraction. This variation is particularly strong around the forward scattering peaks, including sign reversals close to these directions. The results demonstrate that any standard X-ray photoelectron spectroscopy apparatus possesses the potential for combined analysis of surface magnetic structure and geometric structure in a chemically specific way.

The complex magnetoelastic behavior of electroplated NiFeMo/Cu microwires was analyzed by means of the magnetoimpedance and the Procopiu effects. Both phenomena are related through the circular magnetization generated by the ac and were modeled by assuming a magnetic domain and a magnetic relaxation model. From this analysis, information about the frequency and field dependencies of the circular and axial permeabilities was obtained. These results show that the magnetic anisotropy of Cu microwires galvanically coated with a NiFeMo film of 7 μm in thickness is characterized by two circular permeability functions that are ascribed to different types of magnetic domains.

The field and frequency dependences of the magnetic permeability in soft magnetic electroplated FeNiMo/Cu microwires were studied by means of their magneto impedance response. We analysed the influence of electroplating parameters such as current density, electrolyte composition and the presence of a magnetic field. It was found that the introduction of Mo as a third non-magnetic component causes large changes in the film permeability, which are associated with compositional and morphological effects. The electrodeposition under an external magnetic field induces a unidirectional anisotropy with the appearance of a large Barkhausen effect.

Electroplated soft magnetic FeNiMo alloy films on Cu mircrowires show magneto impedance effects larger than 1000%. The magnetic anisotropy generated by the axial deposition of the alloy seems to be an important factor for the achievement of magnetoimpedance. The extent of this effect also increases with the layer thickness. Furthermore, the impedance is markedly improved after the annealing of the coating under an external magnetic field.

The magnetic linear dichroism (MLDAD) in Fe 2p photoemission spectra of an epitaxial ultrathin iron film has been determined. The experiment reveals multiplet related spectra, which allow a detailed characterization of the photoemission process in a simple final state model, that emphasizes the core-valence interaction in Fe 2p photoemission. The same model was used to describe the Cr 2p photoemission spectrum of Cr adsorbates on a Fe surface. The importance of the investigations for the discussion of the 2p photoelectron spectra of 3d metals is pointed out.

We investigated EuO(100) single-crystal surfaces by high-resolution electron energy-loss spectroscopy (HREELS). Not only surface phonons but also dipole-forbidden f–f excitations within the spin-orbit and crystal-field split 7FJ ground state of Eu3+ ions, which are not observable with optical absorption spectroscopy, could be measured. The measurements show that disorder, valence of Eu ions and oxygen content of the near-surface layers are strongly correlated and can vary from sample to sample. The observation of vibrational modes of adsorbed hydroxyl groups and hydrocarbons show that EuO surfaces act in a similar manner onto water and hydrocarbon molecules as transition-metal oxide surfaces do.

Analysis of STM images of Fe grown on Cr and Cr grown on Fe with the exploitation of the differences of the Fe and the Cr surface state energies demonstrates strong intermixing during the epitaxial growth. We suggest a theoretical approach for modelling the epitaxial growth with subsequent self-consistent calculations of electronic and magnetic structure. On the basis of these calculations together with the experimental data obtained by complementary experimental methods, the structure of the interface on the atomic scale and the correlation between the chemical and magnetic roughness are investigated. We show that interface alloying is not symmetrical from both sides of the interface and suggest a scenario of the epitaxial growth that leads to this asymmetry.

The magnetic domain structure of a single crystal of Co (0001) and of polycrystalline AlNiCo was investigated in a photoelectron emission microscope making use of partial restriction of the electron beams. An external movable magnet was used for off-axis deflection of the electron trajectories in the microscope column such that parts of the trajectories are stopped by the apertures of the electron optical elements. As a result, the contrast caused by the stray fields of the magnetic domains is significantly enhanced. The distribution of the local magnetic fields at the surface is reconstructed from the image by means of a theory on the contrast mechanism.

Very high and sensitive magnetoimpedance effect has been studied in FeCoNi magnetic tubes electroplated onto CuBe wire for the frequency of 1MHz order. Strong non-linear effects have been observed. The high harmonics generation was investigated. The harmonics show larger variations with the external field than the fundamental frequency. This super high sensitivity of the harmonics is promising for applications.

We present an experimental setup for in plane two axis magnetometry using the polarization dependent magneto–optic Kerr effect (MOKE). A conventional setup to measure longitudinal MOKE with crossed polarizers is extended by a Faraday cell to compensate for the rotation of the polarization vector caused by a magnetized sample. The shape of the hysteresis loops measured on thin FeNi alloy films depends strongly on the angle between the optical axis of the analyzer and the plane of incidence. We derive expressions for the compensation angle which allow for extraction of vectorial magnetic information from loops detected with oblique polarization. For a small deviation from pure s or p polarization the transverse magnetization is found to be proportional to the difference between the loop obtained with oblique polarization and the one obtained with pure s or p polarization. Thus the complete in plane reversal process split up into longitudinal and transverse components can be observed.

We describe concept, design, and performance of a novel spin polarimeter based on spin-dependent specular reflection of electrons from a Fe(100) surface. The Fe surface is prepared as an ultrathin film on Ag(100). By tuning the energy of the electrons to a critical point in the Fe band structure, a large spin asymmetry combined with a large scattering efficiency is achieved. The polarimeter yields a figure of merit up to 10−2 for the best Fe(100) surfaces.

For two x-ray incidence directions onto an epitaxial FeNi(001) film, one to the left and a second one to the right side of the symmetry plane spanned by the magnetization direction and the photoelectron wave vector, we have measured distributions of the emission-angle dependence with respect to the crystallographic axes of the Fe ${2p}_{3/2}$ core-level photoelectron intensity asymmetry occurring upon magnetization reversal. The two angular distributions transform into each other when the signs of the magnetization and of the photoelectron emission angle are inverted, in accordance with the conservation of parity.

Using the soft-X-ray transverse magnetooptic Kerr-effect at core level thresholds, we have measured hysteresis loops at different locations on a Permalloy stripe structure, supplied by Philips Semiconductors Hamburg. The Permalloy stripes are part of the magnetic field sensors, utilizing the AMR-effect, that are manufactured by Philips Semiconductors. This structure comprised of a stripe array and several additional stripes of different aspect ratios.

We investigated the dipole-forbidden, multiplicity-changing f-f excitations of ${\mathrm{Eu}}^{3+}$ ions by spin polarized electron energy-loss spectroscopy, using a polarized primary electron beam as well as polarization analysis of the scattered electrons. This is the only experimental technique to prove electron-exchange excitations directly. The f-f excitations give rise to a variety of intense sharp structures in the energy-loss range between \ensuremath{\approx}2 and 6 eV. The energy-loss spectra do not change significantly in the primary-energy range between 20 and 100 eV and it could be proved by spin-resolved scattering-geometry dependent measurements that electron exchange is the only excitation mechanism in this energy range. For higher primary energies, the f-f excitation peaks begin to vanish, as expected for excitations by electron exchange, but they reappear at the $4d\ensuremath{-}4f$ threshold because of a resonant enhancement, caused by simultaneous $4f\ensuremath{-}4f$ and $4d\ensuremath{-}4f$ excitations.

The 3s spectra of ferromagnetic Fe and Co were studied by high-resolution spin-resolved photoemission excited by synchrotron radiation. For Fe 3s, data at 500K show a significant broadening of the structure in the polarization spectrum. While some of the features in the spectra can be explained within the framework of an atomic model, some aspects are beyond such a description. This applies to the line shapes and the different binding energies of the leading peaks in the spin-resolved spectrum. The spectra are analysed in terms of statistical moments which provide information on the 3s–3d exchange interaction and the spin moment. The moment of the spin-resolved spectrum is significantly smaller than expected from the values of these quantities, and the result for Co is 13 of that for Fe. This is in conflict with a suggested scaling of this quantity with the expectation value of the z-component of the magnetic moment. The possible influence of majority-polarized satellites with large separation from the main line which have been suggested to be causing the finite spin polarization in the main part of the spectrum is discussed.

We demonstrate the feasibility of the vacuum ultraviolet analog to visible-light magneto-optical imaging of magnetic structures using the resonantly enhanced transverse magneto-optical Kerr effect at core level thresholds with incident p-polarized radiation. The advantages are element specificity and a variable information depth. We used the scanning x-ray microscope at HASYLAB capable of obtaining about 1 μm resolution by means of its focusing ellipsoidal ring mirror. The p-polarized component of the reflected light was selected using multilayer reflection at an additional plane mirror downstream to the sample. Micrographs of the optical reflectivity were taken in the vicinity of the Fe 3p core level threshold at 53.7 and 56.5 eV photon energy where the magneto-optical effect is of opposite sign. Magnetic domains are visible in the difference of both recorded images.

The magnetic structure of ultrathin Cr films on Fe is analyzed by taking into account the roughness of the surface and of the interface. An algorithm for the epitaxial growth of the film simulates the near-surface structure, and the magnetic moment distribution is calculated self-consistently in a periodic Anderson model. For rough interfaces we find that the layered antiferromagnetic structure of the Cr adlayer is quenched. Within this model we determine the spin polarization and the value of the magnetic linear dichroism to be expected in angle-resolved photoemission. Comparing with experimental data it is concluded that Cr grows on the Fe~001! in a Stranski-Kastranoff mode. We propose an explanation based on the confinement of the itinerant electrons within the Cr islands on the Fe substrate. @S0163-1829~99!13801-3#

Results of investigations of Cr overlayers on Fe surfaces by magnetic linear dichroism in the angular distribution and spin-resolved core level photoemission are analysed within the framework of a new model approach. It includes a special algorithm for modelling epitaxial growth of overlayers with different roughness together with self-consistent calculations of the magnetic moment distribution within a Periodic Anderson Model. On this basis the value of the magnetic dichroism and the spin polarisation in photoemission as functions of the Cr coverage can be modelled also for rough surfaces. The comparison of experimental spectra and theoretical coverage dependencies obtained for the different surface roughnesses leads to conclusions about the microscopic structure of Cr overlayers.

By core level x-ray photoelectron spectroscopy using an x-ray tube, ultrathin films of FexNi1-x alloys deposited epitaxially on a Cu(001) substrate have been investigated. Structural information is obtained by means of core level photoelectron diffraction. The angular dependent intensity scans reveal peaks corresponding to a face-centered-cubic lattice in the covered concentration range 0.08<x<0.9. Information on the local magnetic moments is obtained by observing the intensity asymmetry occurring when switching between directions of opposite magnetization (MLDAD) Both the Fe 2p(3/2) and Ni 2p(3/2) asymmetries show a maximum at about 50% Fe concentration. (C) 1999 American Institute of Physics. [S0021-8979(99)72908-7].