Reflectivity and Sherman Maps of Passivated Fe(001): Working Points for a Display-Type Spin-Polarization Analyzer

We explore the Fe(001)-$\mathit{p}(1\times 1)\mathrm{O}$ surface for use as a spin-polarizing mirror to implement spin sensitivity in display-type electron analyzers. We perform spin-dependent low-energy electron reflection measurements over a wide range of incident electron energies and angles. We derive maps of reflectivity, the Sherman function, and figure of merit. Several working points are identified. A maximum figure of merit of $2.8\times {10}^{-2}$ is found at an incidence angle of 58° and a kinetic energy of 2.8 eV.

Figure 1

Experimental setup. A spin-polarized electron beam is directed onto a magnetized target at an incidence angle $\mathrm{\Theta }$. The spin polarization $\mathbf{P}$ and the magnetization $\mathbf{M}$ lie in the scattering plane. In this geometry, spin-orbit effects are excluded. The specularly reflected current $I$ is detected with a Faraday cup, which can be rotated around the target. The incident current $I_0$ is measured with the detector in the $I_0$ position when the target is removed.

Figure 2

Spin-resolved low-energy electron reflection measurements for two selected angles of incidence $\mathrm{\Theta }=27°$ (filled circles) and $\mathrm{\Theta }=45°$ (open circles). The top panel shows the reflectivity $R=I/I_0$, the second panel shows the Sherman function $S$, and the two lower panels show the FOM and FOM*. The FOM is calculated for our experimental geometry, while the FOM* is derived for a collinear configuration of $\mathbf{P}$ and $\mathbf{M}$.

Figure 3

Reflectivity $R$ (upper row), Sherman function $S$ (second row), and FOM and FOM* (lower rows) as a function of incidence angle $\mathrm{\Theta }$ and kinetic energy for opposite magnetization directions $\uparrow$ and $\downarrow$ of the passivated iron target. The FOM is calculated for our experimental geometry, while the FOM* is derived for a collinear configuration of $\mathbf{P}$ and $\mathbf{M}$. Contour lines are shown for 0.5, 1.0, 1.5, 2.0, and $2.5\times {10}^{-2}$ in the lower left-hand panel.