A Bolt-On Source of Spin Polarised Electrons for Studies of Surface Magnetism

Abstract

Experiments with spin-polarised electrons are rapidly gaining importance due to their ability to selectively measure the exchange-split majority- and minority-spin electronic states. By employing the inverse photoemission process with its small probing depth, information about surface magnetism can additionally be obtained. In this chapter a description will be given of a versatile and transportable spin-polarised electron gun for angle-resolved spin-polarised inverse photoemission spectroscopy (ARSPIPES) experiments. A GaAs(001) single crystal is employed to obtain spin-polarised electrons by photoemission with circularly polarised light. To obtain a transversely polarised beam, which has the objective of optimising the spin-dependent interaction with a sample magnetised in the surface plane, a 90° electrostatic spherical sector is used to deviate the direction but not the spin of the electrons. A set of electrostatic lenses are employed in order to transport and focus the electrons onto a target of investigation. A brief description of results obtained with this apparatus will be given.