Secondary emission from W(1 1 0) excited by spin-polarized electrons S. Samarin a, * , O.M. Artamonov b , A.D. Sergeant a , J.F. Williams a a Centre for Atomic, Molecular and Surface Physics, University of Western Australia, Perth, WA 6009, Australia b Research Institute of Physics, St. Petersburg University, St. Petersburg 198904, Russia Received 5 November 2004; accepted for publication 27 January 2005 Abstract Energy distribution curves (EDC) of secondary electrons from W(1 1 0) were measured for spin-up (I + ) and spin- down (I  ) polarization of the incident beam. The intensity asymmetry, defined as A =(I +  I  )/(I + + I  ), for a certain experimental geometry was measured as large as 7%. This asymmetry was explained in terms of a ‘‘spin-filter’’ effect. The model assumes that the secondary electrons excited by spin-polarized primary electrons are spin-polarized inside the solid. On the way to the vacuum they undergo spin–orbit interaction on the surface barrier that provides the spin- dependent and energy selective transmission through the surface. Ó 2005 Elsevier B.V. All rights reserved. Keywords: Secondary electron emission; Spin-polarized electrons; Tungsten 1. Introduction Secondary electron emission from a tungsten crystal, excited by electrons of various energies, is well studied both theoretically and experimen- tally [1–4]. The elastic scattering of spin-polarized electrons from tungsten was found to be very dependent on electron energy and scattering angle [5,6]. It was also reported [7] that the secondary emission yield r depends on the spin polarization of the incident beam. However, there are no systematic measurements of energy distribution curves (EDC) of secondary electrons from tung- sten excited by spin-polarized electrons. Elastic and inelastic scattering of spin-polarized electrons from a solid surface depends, in general, on the orientation of the polarization vector of the incident beam with respect to a quantization axis. This dependence is caused by two effects: exchange interaction and spin–orbit interaction (SOI). Both of these effects are present when an electron is 0039-6028/$ - see front matter Ó 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.susc.2005.01.046 * Corresponding author. Address: Physics, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia. Tel.: +61 8 9380 3479; fax: +61 8 9380 1014. E-mail address: samar@physics.uwa.edu.au (S. Samarin). Surface Science 579 (2005) 166–174 www.elsevier.com/locate/susc