  A first principles approach for spin and angle resolved resonant
photoemission is developed within multiple scattering theory and applied to a
Cr(110) surface at the 2$p$-3$d$ resonance. The resonant photocurrent from this
non ferromagnetic system is found to be strongly spin polarized by circularly
polarized light, in agreement with experiments on antiferromagnetic and
magnetically disordered systems. By comparing the antiferromagnetic and
Pauli-paramagnetic phases of Cr, we explicitly show that the spin polarization
of the photocurrent is independent of the existence of local magnetic moments,
solving a long-standing debate on the origin of such polarization. New spin
polarization effects are predicted for the paramagnetic phase even with
unpolarized light, opening new directions for full mapping of spin interactions
in macroscopically non magnetic or nanostructured systems.
