Search results for "circular"
showing 10 items of 856 documents
Threshold photoemission magnetic circular dichroism at the spin-reorientation transition of ultrathin epitaxial Pt/Co/Pt(111)/W(110) films
2009
X-ray magnetic circular dichroism (MCD) is nowadays widely used for the investigation of magnetic properties of surfaces and thin films. Recently, similarly large effects have been observed for UV-VIS MCD effects both in single [1] and two-photon photoemission [2-3]. This threshold MCD effect is directly related to spin-orbit effects present at the Fermi edge. We report on the observation of threshold photoemission magnetic circular dichroism (TPMCD) in one-photon and two-photon photoemission (1PPE and 2PPE) at a Pt-capped ultrathin Co wedge grown on Pt(111)/W(110) using femtosecond laser light. TPMCD measurements result in asymmetries continuously increasing with the sample thickness. This…
Photocatalytic activity of non-stoichiometric ZnFe2O4under visible light irradiation
2014
Nanostructured zinc ferrites with different excess iron contents (ZnFe2+zO4, where z = 0.00, 0.05, 0.10 and 0.15) have been synthesized using the sol–gel auto-combustion method. The effect of excess iron on the structural, optical and visible light photocatalytic activity of zinc ferrite samples has been investigated. X-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), x-ray magnetic circular dichroism (XMCD), Brunauer–Emmett–Teller theory, scanning electron microscopy (SEM), diffuse reflectance spectroscopy (UV–Vis) and photoluminescence spectroscopy were used to characterize the synthesized non-stoichiometric ZnFe2O4 powders. The XRD patterns demonstrated that the samples con…
Origin of Kerr effect: investigation of solutions by polarization dependent Z-scan
2020
This material is based upon work supported by the ERDF 1.1.1.1 activity project No. 1.1.1.1/16/A/046 “Application assessment of novel organic materials by prototyping of photonic devices”.
Element-Selective Magnetic Imaging in Exchange-Coupled Systems by Magnetic Photoemission Microscopy
1998
We have used a photoemission microscope to obtain element-resolved magnetic contrast in stacked magnetic thin film systems. Magnetic information is thereby provided by X-ray magnetic circular dichroism. Elemental sensitivity, which is crucial for studying magnetic coupling phenomena in systems with several different layers, is achieved by tuning the energy of the illuminating photons to atomic absorption edges. We present measurements of a Ni-coated Co micropattern on Cu(001), and a wedged Co/Cr/Fe(001) sample. In the former sample the Ni magnetization is seen to follow the magnetization of the Co pattern, thereby changing from an out-of-plane easy axis in areas without underlying Co to in…
Direct imaging of delayed magneto-dynamic modes induced by surface acoustic waves.
2017
The magnetoelastic effect—the change of magnetic properties caused by the elastic deformation of a magnetic material—has been proposed as an alternative approach to magnetic fields for the low-power control of magnetization states of nanoelements since it avoids charge currents, which entail ohmic losses. Here, we have studied the effect of dynamic strain accompanying a surface acoustic wave on magnetic nanostructures in thermal equilibrium. We have developed an experimental technique based on stroboscopic X-ray microscopy that provides a pathway to the quantitative study of strain waves and magnetization at the nanoscale. We have simultaneously imaged the evolution of both strain and magne…
Epitaxial films of the magnetic shape memory material
2007
Abstract By DC-sputtering from a stoichiometric target onto sapphire substrates we prepared epitaxial films of Ni 2 MnGa . X-ray diffraction in two circle geometry shows only the Ni 2 MnGa peaks corresponding to a (1 1 0) oriented growth on the (1 1 0) oriented sapphire substrate. Rocking curve scans shows that the out of plane orientation has a width of only 1 . 1 ∘ . By four circle X-ray diffraction we find an in-plane aligned growth. The Curie temperature as determined by SQUID magnetometry is 368 K. On cooling down the low field magnetization drops at around 260–280 K indicating the austenite to martensite transition. The presence of two different phases at high and low temperature also…
Valorisation of urban green areas for producing renewable energy and biochar as growing substrate of Sicilian aromatic and nutraceutical species in a…
2020
This work is aimed at evaluating the possible building up of a gasifier for the energy valorisation of residual biomass deriving from urban areas and their surroundings. The area and the volumes of supply and economic convenience have been determined by implementing a GIS-based geographic method to the localisation and quantification of non-uniform elements of plant biomass. The pyrolysis and gasification processes of the lignocellulosic biomass obtained from pruning and maintenance operations of the urban and ornamental green include the production of a residual amount of biochar. The biochar can be used in agriculture as a soil improver and a substrate alternative to peat in the sustainab…
Epitaxial film growth and magnetic properties ofCo2FeSi
2006
We have grown thin films of the Heusler compound ${\mathrm{Co}}_{2}\mathrm{Fe}\mathrm{Si}$ by RF magnetron sputtering. On (100)-oriented MgO substrates we find fully epitaxial (100)-oriented and $L{2}_{1}$ ordered growth. On ${\mathrm{Al}}_{2}{\mathrm{O}}_{3}(11\overline{2}0)$ substrates, the film growth is (110)-oriented, and several in-plane epitaxial domains are observed. The temperature dependence of the electrical resistivity shows a power law with an exponent of $7∕2$ at low temperatures. Investigation of the bulk magnetic properties reveals an extrapolated saturation magnetization of $5.0{\ensuremath{\mu}}_{B}∕\mathrm{f.u.}$ at $0\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. The films on $…
Spin-polarized photoelectrons resonantly excited by circularly polarized light from a fractional Ag film on GaAs(100)
2013
We demonstrate a finite spin polarization of photoelectrons emitted from GaAs(100) covered by a fractional Ag film. The photoemission yield shows a sharp maximum for intermediate coverage and the spin polarization increases with increasing laser intensity. Photoelectrons are excited by circularly polarized 100 fs laser pulses of 800 nm wavelength. We recorded the photoemitted electrons using a photoemission electron microscope combined with a Mott spin polarimeter. The spin polarization is analyzed in dependence on the excitation frequency and intensity and on the average thickness of the silver film. The results are explained by a model combining multiphoton photoemission and optical field…
Solvent-induced high-spin transition in double-decker 3d–4f metallacrowns
2019
Element-specific magnetic spin and orbital magnetic moments of $3d\text{\ensuremath{-}}4f$ double-decker metallacrown molecules have been investigated using x-ray magnetic circular dichroism. The double-decker metallacrowns comprise one rare-earth Gd(III) or Tb(III) ion embedded between two squared scaffolds of four Ni(II) ions. We observe a strong increase of the Ni(II) moments if the molecules are dissolved in methanol, indicating a spin crossover from a low-spin to a high-spin state. In contrast, dichloromethane does not change the spin state. This result is explained by a change of the coordination environment of nickel. The comparison of charge-transfer multiplet calculations with the …