G. A. Mulhollan

Adapting a compact Mott spin polarimeter to a large commercial electron energy analyzer for spin‐polarized electron spectroscopy

A modified Rice University‐type compact Mott spin polarimeter operating at 20 kV is adapted to a large commerical hemispherical electron energy analyzer. Normal energy analyzer functions are preserved via a retractable channeltron in the polarimeter acceleration column. In the spin‐detection mode, the polarimeter permits analysis of two orthogonal transverse spin‐polarization components. Electron trajectory analysis is used to optimize polarimeter lens column voltages in both normal and spin‐detection modes. Performance levels are established by experiments and significantly improved spin‐detection efficiency is shown to be accessible by changes in the polarimeter collection solid angle.

Influence of surface atomic steps on in‐plane magnetic anisotropy of ultrathin Fe films on W(001)

Previous magneto‐optic Kerr effect studies of ultrathin epitaxial Fe films grown on stepped W(001) surfaces yielded evidence of in‐plane uniaxial magnetic anisotropy with magnetization perpendicular to the steps. We report spin‐polarized secondary electron emission spectroscopy studies of the same system that confirms this novel micromagnetic phenomena, and provides a more detailed characterization of the zero‐field in‐plane spin configuration as a function of initial applied field direction.

Spin and angle‐resolved photoemission studies of one to three monolayer films of p(1×1) Fe on W(100)

The electronic and magnetic properties of thin (one to three monolayer) epitaxial Fe films grown on W(100) are studied using spin‐polarized angle‐resolved photoemission. Low‐energy electron‐diffraction studies of a number of samples confirm excellent epitaxy for monolayer films and suggest that two‐ and three‐layer films begin to form strain‐relieving dislocations. Submonolayer films manifest no in‐plane remanent spin polarization at T=115 K, but effectively quench W(100) surface states and surface resonances. Monolayer and thicker films yield spin‐polarized photoelectrons under remanent magnetic conditions. Analysis of spin‐polarized electron energy distribution curves (EDCs) corresponding to even‐symmetry initial states along the Γ‐M direction of the two‐dimensional Brillouin zone yields a flat majority‐spin band at 0.95 eV and an exchange split pair of bands (ΔEexΔEex= 2.15 ± 0.2 eV at Γ, 1.2±0.2 eV at M) which exhibit significant dispersion. No significant changes in the binding energies of spin‐u...

A simple substitute for Knudsen cells using an existing pendant-drop type electron beam evaporator

A simple and elegant technique is outlined in which a specially designed crucible may be used for noble metal evaporation in a pendant‐drop type electron beam evaporator with virtually no modifications.

Hydrogen induced coercivity changes in monolayer films of Fe/W(110)

The effects of hydrogen exposure on the coercivity of monolayer (ML) films of Fe/W(110) are explored with the magneto‐optical Kerr effect. A large increase in coercivity with exposure occurs simultaneously with a much smaller decrease in saturation magnetization. These changes are shown to be related to the hydrogen coverage of the surface and are accounted for by a simple model based on non magnetic inclusions embedded in a magnetic material.