Spin-polarized photoemission

  • P. D. JohnsonEmail author
Part of the Condensed Matter book series (volume 45B)


In this chapter the theory behind the spin-polarized photoemission process is discussed in detail.

We will make reference in this chapter to experiments using the technique of spin-polarized photoemission where the spin of the electron is measured as well as the energy and momentum. Again we will not provide any detailed description of experimental apparatus as these have been reviewed extensively elsewhere [97J1]. Suffice it to say that spin detection involves either measuring the spin asymmetry in the scattering of the photoemitted electrons from a ferromagnetic surface or the scattering of the electrons from heavy atoms using the spin-orbit interaction to distinguish the two spin states. Either way spin polarimeters are compared through their figure of merit (FOM) which is given by
$$ \mathrm{FOM}={S}^2\frac{I}{I_0} $$
where S, the Sherman function, is a measure of the ability of the device to distinguish different spins, I is the total scattered current collected by the device, and I0 is the incident current. The spin polarization of the incident beam P is given by
$$ P=\frac{1}{S}\frac{I_A-{I}_B}{I_A+{I}_B} $$
where IA and IB are the currents measured in two opposite scattering channels. Having measured the polarization P, the individual spin-resolved spectra are obtained via the expressions
$$ {I}^{\uparrow }=I\left(1+P\right)/2\kern2.77695pt \mathrm{and}\kern2.77695pt {I}^{\downarrow }=I\left(1+P\right)/2 $$

As in the case of regular photoemission, the time reversal of this process allows for the investigation of the spin of unoccupied states. However, in such experiments the key requirement becomes the need for a spin-polarized electron source.

Symbols and abbreviations

Short form

Full form


figure of merit


  1. [97J1]
    Johnson, P.D.: Rep. Prog. Phys. 60, 1217 (1997)ADSCrossRefGoogle Scholar

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© Springer-Verlag GmbH Germany 2018

Authors and Affiliations

  1. 1.Condensed Matter Physics and Materials Science DepartmentBrookhaven National LabUptonUSA

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