Angle-resolved inverse photoemission spectroscopy with longitudinally spin-polarized electrons

Abstract

We have built and tested a spin-polarized electron source based on photoemission from negative electron affinity GaAs(100). It provides 5-10 μA of longitudinally spin-polarized electrons in the energy range 5-20 eV. Following the design of Erdman and Zipf, the electron optics are simple and consist of only five elements. Their voltages are all proportional to each other and are linearly driven by one ramping voltage. The spin-polarized electrons are used for angle-resolved inverse photoemission measurements from magnetized sample surfaces. Our first results obtained from Ni(110) mounted on a horseshoe magnet agree well with the literature. From these measurements the degree of spin polarization is determined to be 35%±5%. We also checked the spin polarization using an absorbed-current spin detector in combination with a 90° cylindrical deflector.