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[Display omitted] • Fe and Ni multilayer epitaxy is realized on oxygen-passivated Fe(0 0 1). • Oxygen floats on the surface and affects the magnetic response of the system. • The spin polarization of the photoemission signal is quenched upon Ni growth. • A single Fe layer abruptly restores the polarization signal. • According to simulations, the spectral polarization follows surface magnetization. We investigated the magnetic behaviour of an Fe overlayer on a Ni buffer layer (Fe/Ni multilayer system) grown on top of the Fe- p (1 × 1)O surface, with a particular focus on the modifications observed in the spin-resolved electronic structure and the role of oxygen, introduced in the system in a well-defined amount at the substrate preparation stage. The structural properties are investigated by means of low energy electron diffraction, that confirms the formation of an epitaxial system featuring a metastable surface lattice. Spin-resolved photoemission spectroscopy testifies a strong decrease of the spectral spin polarization for increasing thickness of the Ni buffer layer, reaching a minimum from a nominal thickness of 6 Ni atomic layers. Surprisingly, the growth of a single Fe overlayer is sufficient to restore most of the original polarization signal, thus creating an ultrathin bcc Fe film seemingly decoupled from the substrate. Ab initio calculations track the modifications of the magnetic moments of the surface layers that quench upon Ni deposition and restore with additional Fe growth. Spin-resolved inverse photoemission highlights a notable reduction of the density of majority states just above the Fermi level, possibly influencing the magnetic response of the system. [ABSTRACT FROM AUTHOR]

We have designed and constructed a spin polarized low energy electron diffraction system working in the reflected electron pulse counting mode. This system is capable of measuring asymmetries due to spin-orbit and exchange interactions. Photoemission from a strained GaAs/GaAsP super lattice is used as the source of spin polarized electrons. Spin-orbit asymmetry is evaluated for Ir(100) single crystal at various energies. Subsequently, exchange asymmetry has been evaluated on 40 monolayer Fe deposited on Ir(100). This instrument proves to be useful in understanding structure and magnetism at surfaces. [ABSTRACT FROM AUTHOR]

The construction of a multichannel vector spin polarimeter requires the development of a detector type, which works as a spin polarizing mirror with high reflectivity and asymmetry properties to guarantee for a high figure of merit. Technical realizations are found by spin-polarized electron scattering from a surface at low energies. A very promising candidate for such a detector suitable material consists of an oxygen passivated iron surface, as for example a Fe(001)-p(1×1)O surface. We investigate in detail the electronic structure of this adsorbate system and calculate the corresponding spin-polarized low-energy electron scattering. Our theoretical study is based on the fully relativistic SPRKKR method in the framework of density functional theory. Furthermore, we use the local spin-density approximation in combination with dynamical mean field theory to determine the electronic structure of Fe(001)-p(1×1)O and demonstrate that a significant impact of correlation effects occurs in the calculated figure of merit. [ABSTRACT FROM AUTHOR]

We describe the principle, the preparation, and the calibration of a spin-polarizing electron mirror in multichannel spin polarimetry. We show data obtained by two independent devices (a goniometer-type LEED set-up and a momentum-microscope set-up) and compare them to the results of a relativistic multiple scattering theory. We also discuss the effects of misalignment and mosaic structure of the crystal. For multi-channel detection we find a 5000-fold increase of efficiency over a single-channel spin-detector. The lifetime of the detector is more than 6 months in ultra-high vacuum. [ABSTRACT FROM AUTHOR]

Abstract: Using a photoelectron emission microscope (PEEM), we demonstrate spin-resolved electron spectroscopic imaging of ultrathin magnetic Co films grown on Cu(100). The spin-filter, based on the spin-dependent reflection of low energy electrons from a W(100) crystal, is attached to an aberration corrected electrostatic energy analyzer coupled to an electrostatic PEEM column. We present a method for the quantitative measurement of the electron spin polarization at 4×103 points of the PEEM image, simultaneously. This approach uses the subsequent acquisition of two images with different scattering energies of the electrons at the W(100) target to directly derive the spin polarization without the need of magnetization reversal of the sample. [Copyright &y& Elsevier]

Abstract We present a series of theoretical spin-polarized diffuse low-energy electron diffraction studies which explore the information that may be extracted from the rotation curves. At selected beam energies, we report calculations of the angular variations of the relativistic incoherent intensity along with the spin–orbit induced incoherent scattering asymmetry. Both the polar angle of incidence and the azimuthal angle of incidence of a polarized beam are scanned consecutively. Through use of relativistic multiple scattering theory of diffuse LEED, we study the particular advantages of using DSPLEED rotation curves for the disorder surface structure analysis. We explore the CO/Pt(111) system, focusing on the sensitivity of features in the rotation curves to some aspects of adsorbate/substrate geometry. For example, the incoherent asymmetry parameters prove to be very sensitive to the adsorbate/substrate spacing. [ABSTRACT FROM AUTHOR]

• We report on the growth and characterization of Fe/Co bilayers on bcc W(110). • The bottom Co layer relaxes to its bulk hcp structure showing an hexagonal surface. • Even with the Co layer, we detect Fe relaxation with the formation of bcc nuclei. • We measure a not nil in-plane spectral spin polarization at magnetic remanence. We report on the growth of a Fe/Co bilayer on W(110) and its electronic and magnetic structure characterization by means of low energy electron diffraction and spin-resolved photoemission spectroscopies. The Co bottom layer, investigated in the thickness range from 2 to 10 monolayers (ML), relaxes immediately to its bulk hcp structure and is therefore used to provide an hexagonal top surface for the growth of metastable Fe films. Notwithstanding the presence of the Co layer, and similar to our previous findings concerning the growth of Fe on a Ni layer [Phys Rev B 94 195155], we report the formation of bcc nuclei, indicative of lattice relaxation, even for a Fe thicknesses as low as 2 ML. For all the Fe/Co thickness combinations and at magnetic remanence, we were able to measure a not nil in-plane spectral spin polarization. [ABSTRACT FROM AUTHOR]

The construction of a multichannel vector spin polarimeter requires the development of a detector type, which works as a spin polarizing mirror with high reflectivity and asymmetry properties to guarantee for a high figure of merit. Technical realizations are found by spin-polarized electron scattering from a surface at low energies. A very promising candidate for such a detector suitable material consists of an oxygen passivated iron surface, as for example a Fe(001)-p(1×1)O surface. We investigate in detail the electronic structure of this adsorbate system and calculate the corresponding spin-polarized low-energy electron scattering. Our theoretical study is based on the fully relativistic SPRKKR method in the framework of density functional theory. Furthermore, we use the local spin-density approximation in combination with dynamical mean field theory to determine the electronic structure of Fe(001)-p(1×1)O and demonstrate that a significant impact of correlation effects occurs in the calculated figure of merit. [ABSTRACT FROM AUTHOR]