R. Metzke et W. Nolting, SPIN-FILTER EFFECT OF THE EUROPIUM CHALCOGENIDES - AN EXACTLY SOLVED MANY-BODY MODEL, Physical review. B, Condensed matter, 58(13), 1998, pp. 8579-8589
A model Hamiltonian is introduced which considers the main features of
the experimental spin-filter situation such as s-f interaction, plana
r geometry, and the strong external electric field. The proposed many-
body model can be solved analytically and exactly using Green function
s. The spin polarization of the field-emitted electrons is expressed i
n terms of spin-flip probabilities, which are put down to the exactly
known dynamic quantities of the system. The calculated electron spin p
olarization shows remarkable dependencies on the electron velocity per
pendicular to the emitting plane and the strength of s-f coupling. Exp
erimentally observed polarization values of about 90% are well underst
ood within the framework of the proposed model.