A variable-angle electron spin polarization detection system

An ultrahigh vacuum apparatus for investigations of ferromagnetic samples allowing the variation of detection angle and spin resolution of secondary and photoelectrons is described. Angle variation is facilitated by a special combination of 180 degrees and 90 degrees deflectors and a cylindrical sector analyzer serves as energy dispersing element. Spin analysis is carried out using a hemispherical high energy (90 keV) Mott polarimeter without retarding potentials. Its efficiency was determined as 2.4 x 10(-4). Due to acceleration in a short spherically symmetric field, the setup is rather compact and the sensitivity to geometrical misalignment is small. The performance of the instrument is demonstrated by angle dependent measurements of thin ferromagnetic Co(0001) films, evaporated on W(110), and modifications of surface magnetic properties of a xenon adsorbate layer. (C) 1998 American Institute of Physics. [S0034-6748(98)01611- 6].