  We use a ferromagnetic voltage probe model to study the influence of
inelastic scattering on giant magnetoresistance and current-induced torques in
ferromagnetic and antiferromagnetic metal spin valves. The model is based on
the Green's function formulation of transport theory and represents
spin-dependent and spin-independent inelastic scatterers by interior voltage
probes that are constrained to carry respectively no charge current and no spin
or charge current. We find that giant magnetoresistance and spin transfer
torques in ferromagnetic metal spin valve structures survive arbitrarily strong
spin-independent inelastic scattering, while the recently predicted analogous
phenomena in antiferromagnetic metal spin valves are partially suppressed. We
use toy-model numerical calculations to estimate spacer layer thickness
requirements for room temperature operation of antiferromagnetic metal spin
valves.
