Sensitivity to Spin Polarization

The occurrence of a difference in the intensities of the ejected electrons with different spin directions by interacting of a spin polarized metastable He(2 5) 

In the depicted case in Fig. 2.7 only a minority electron can fill the li hole, when exciting with He(2 S) atoms, leading to an intensity f of the escaping 2s electrons. By exciting with He(2 S) atoms, only majority electrons can tunnel to the helium atom leading to an electron intensity 7. For ferromagnetic materials the spin resolved densities of states are different for majority and minority electrons (schematically shown on the left hand side of Fig. 2.8). Thus, the asymmetry A, normalized to the polarization of the incident atomic beam with polarization Pa corresponds to the difference in the DOS for the majority and minority electrons  

Due to the surface sensitivity of MDS and the spin selectivity of the de-excitation process, properties of the spin resolved DOS of the outermost layer can therefore be obtained. 

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