Spin-polarized Electron Diffraction Research Articles

Determination of surface and interface magnetic properties for the multiferroic heterostructure Co/BaTiO3 using spleed and arpes

Co/BaTiO3(0 0 1) is one of the most interesting multiferroic heterostructures as it combines different ferroic phases, setting this way the fundamentals for innovative technical applications. Various theoretical approaches have been applied to investigate the electronic and magnetic properties of Co/BaTiO3(0 0 1). Here we determine the magnetic properties of 3 ML Co/BaTiO3 by calculating spin-polarized electron diffraction as well as angle-resolved photoemission spectra, with both methods being well established as surface sensitive techniques. Furthermore, we discuss the impact of altering the BaTiO3 polarization on the spectra and ascribe the observed changes to characteristic details of the electronic structure.

Coverage-dependent diffuse spin-polarized electron diffraction analysis of CO on Pt( [formula omitted

The coverage dependence of the local adsorption structure of carbon monoxide on Pt(1 1 1) is investigated by means of diffuse spin-polarized electron diffraction (DSPLEED). We present the theoretical discussion of the scattering of spin-polarized electrons from the disordered CO layer adsorbed on the Pt(1 1 1) surface. The spin-dependent diffuse low-energy electron diffraction (LEED) intensity and the resulting diffuse scattering asymmetry parameter are calculated for different adsorption structures of CO connected with different coverages. We report the energy as well as the angular dependence of the diffuse relativistic intensity and of the spin–orbit asymmetry. We explore the information that may be extracted from the DSPLEED rotation curves which are calculated at a selected beam energy. The polar angle of incidence of a polarized beam is held fixed and the azimuthal angle is scanned. We are focusing on the sensitivity of features in the rotation curves to the coverage-dependent structure of the adlayer keeping other geometrical parameters of the CO/Pt(1 1 1) system fixed. We find the rotation curves to be very sensitive with respect to the correlation effects governing the adlayer formation while the energy-dependent DSPLEED spectra do not expose such strong dependency.

Paramagnetic fluctuationsin MnO

A shift in the muon spin-relaxation rate in MnO is observed around 540 K, i.e. about 4.5 times TN. This result confirms earlierobservations using spin-polarized electron diffraction of asignificant change in the paramagnetic spin system taking place at thistemperature. This change might be caused by the transition from astate with correlated magnetic clusters to independently fluctuatingspins. Furthermore, we have confirmed previous findings that at lowtemperature, the implanted muons are situated at sites close tomanganese ions and that, as the temperature is increased, they diffuseand are trapped at manganese vacancies. In addition, we have observedthat the muons are detrapped and start to diffuse again attemperatures above 800 K.

Submonolayer magnetism of Fe(110) on W(110): Finite width scaling of stripes and percolation between islands.

Relations between magnetism and morphology in submonolayer films of Fe(110) on W(110) were studied using spin polarized electron diffraction and scanning tunneling microscopy. Films prepared at 600 K form monolayer stripes along with the W steps; they are ferromagnetic with ${T}_{c}$ slowly decreasing from 225 K near $\ensuremath{\theta}=1 \mathrm{to} 180$ K near $\ensuremath{\theta}=0.1$. The decrease scales with $\frac{1}{\ensuremath{\theta}}$. Films prepared at 300 K nucleate by islands which start to coalesce near $\ensuremath{\theta}=0.6$. For $\ensuremath{\theta}\ensuremath{\le}0.58$, they are superparamagnetic at $T\ensuremath{\ge}115$ K. In a narrow $\ensuremath{\theta}$ range of only 2%, magnetic percolation occurs, resulting in ferromagnetism with ${T}_{c}\ensuremath{\ge}190$ K for $\ensuremath{\theta}\ensuremath{\ge}0.60$.

Spin-polarized electron diffraction from Pb(110): Surface barrier and non-spherical potential effects

Intensity and polarization spectra of the specular beam in spin-polarized low-energy electron diffraction (SPLEED) from Pb(110) have been measured - using a polarized-electron gun - and calculated by means of a fully relativistic multiple scattering formalism. Comparison between experiment and theory supports multilayer relaxation. At very low energy, surface barrier resonances in the spin-asymmetry spectra were observed and theoretically reproduced. Non-spherical contributions to the crystal-atom potential are visible in the theoretical results but smaller than remaining discrepancies with the experimental data.

Very-low-energy spin-polarized electron diffraction from Fe(001)

The reflection coefficient in very-low-energy spin polarized electron reflection from magnetized Fe(001) has been investigated in the energy range 0<E<23 eV. A peak in the asymmetry of 21% is observed atE=10.6 eV with a mean reflection coefficient ≈0.1. This effect provides a new spin detector with a more than 20 times larger efficiency than with other spin detectors.

Simultaneous probing of exchange and spin-orbit interaction in spin polarized low energy electron diffraction from magnetic surfaces

An experimental set-up allowing simultaneous probing of exchange and spin-orbit scattering in spin polarized electron diffraction (SPLEED) from magnetic surfaces is described. In a theoretical analysis it is made clear why the measured scattering asymmetries are, in very good approximation, linear superpositions of the exchange and spin-orbit asymmetries. As an illustration SPLEED data for Ni (001) collected at various energies and angles of incidence of the primary beam, are presented and shown to be in good agreement with theoretical results.