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Spin-polarized scanning tunneling microscopy has produced a great amount of images presenting magnetic contrast between different magnetic domains with an unsurpassed spatial resolution but getting values like the surface polarization has proven to be a difficult task. We will discuss in detail how to extract this information for the case of manganese layers grown on Fe(001) whiskers. Mn layers adopt a body-centered-tetragonal (bct) structure when they are grown on the Fe(001) surface at room temperature. The Mn layers show an antiferromagnetic coupling between the layers. Comparing our spin-polarized scanning tunneling spectra measured with Fe-coated W tips with spin-resolved band structure calculations, we are able to find the value of the sample surface polarization. Also discussed is a method to change the tip magnetization. Finally, the magnetic structure around a screw dislocation on the surface is reviewed., ((c) 2005 Wiley-Liss, Inc.)

The present letter describes a method to make a spin-polarized scanning tunneling microscopy tip by applying voltage pulses between a W tip and a magnetic sample. This spin-polarized tip has the similar characteristics as an Fe-coated W tip, which was confirmed by observations of antiferromagnetically coupled ferromagnetic Mn(001) layers (> 3 ML) grown on an Fe(001) whisker at 370 K. Furthermore, we demonstrate that these voltage pulses can vary the tip magnetization direction. [ABSTRACT FROM AUTHOR]

To elucidate the magnetic properties of a magnetic multilayer film, an understanding of the local geometry, electronic structure, and possible intermixing at the interfaces is of utmost importance. By gradually increasing the Fe coverage on the Mn(0 0 1) film, we obtained this information on the interface region by means of Auger spectroscopy and scanning tunneling microscopy/spectroscopy. Intermixed atoms and various geometries and density of states are found to exist in this system. [Copyright &y& Elsevier]

The growth of ultrathin Mn films on an Fe(0 0 1) whisker at 370 K is studied by scanning tunneling microscopy (STM) and scanning tunneling spectroscopy at room temperature in ultrahigh vacuum. Atomically and chemically resolved STM images show that the Mn film grows with the same in-plane lattice constant as Fe(0 0 1) and that Fe atoms intermix with the first (14%), the second (4%), and the third Mn layer (2%), while a negligible amount of Fe atoms is found above the third layer. The growth mode changes from layer-by-layer to layer-plus-island at a coverage of 3 ML Mn. dI/dV curves which are normalized by voltage-dependent tunneling probability functions show clear peaks on each Mn layer. These peaks are tentatively ascribed to surface states. On the first Mn layer, peaks are found at +0.35 eV on pure Mn areas and at +0.28 eV on mixed MnFe areas. The second and the third Mn layer show peaks at +0.20 and +0.8 eV, respectively. Mn films thicker than three layers reveal besides a strong peak at +0.8 eV a weaker peak at −0.6 eV. Our apparent step height measurements show that the Mn film relaxes at the third layer: the interlayer spacing is ∼0.16 nm for the first two layers, and it increases to ∼0.18 nm at the third layer. Starting from the fourth layer the interlayer spacings are geometrically equivalent (∼0.165 nm). [Copyright &y& Elsevier]

The submonolayer growth of Mn on Fe(0 0 1) in the temperature range between 50 and 200 °C is studied by scanning tunneling microscopy and scanning tunneling spectroscopy. For growth temperatures above 100 °C, atomically resolved STM images with chemical contrast clearly reveal the incorporation of Mn atoms in the Fe(0 0 1) substrate. The fraction of place exchanged Mn atoms is observed to increase with growth temperature. Although on islands a c(2×2) structure forms locally which is attributed to an ordered MnFe surface alloy, long range order could not be obtained for the growth temperatures and coverages studied. Spectroscopy results are presented for clean Fe(0 0 1), pure Mn ad-islands, single incorporated Mn atoms and c(2×2)-ordered MnFe areas. In contrast to embedded Cr atoms in the Fe(0 0 1) surface [Phys. Rev. Lett. 76 (1996) 4175], isolated embedded Mn atoms do not lead to double peak structures in dI/dV curves. Nevertheless, on the ordered c(2×2) MnFe structure and the pure Mn monoatomic islands surface states are detected as peaks in the dI/dV and (dI/dV)/(I/V) curves. However, due to the strong influence of a tip-dependent background on these peaks, the corresponding surface state energies cannot be found directly from those curves. The real surface state energies were recovered by normalizing the measured dI/dV curves by fitted quadratic backgrounds. Thus, surface state energies of about +0.35 and +0.25 eV are estimated for pure Mn islands and alloyed MnFe areas, respectively. [Copyright &y& Elsevier]