  Angular variation of giant magnetoresistance and spin-transfer torque in
metallic spin-valve heterostructures is analyzed theoretically in the limit of
diffusive transport. It is shown that the spin-transfer torque in asymmetric
spin valves can vanish in non-collinear magnetic configurations, and such a
non-standard behavior of the torque is generally associated with a
non-monotonic angular dependence of the giant magnetoresistance, with a global
minimum at a non-collinear magnetic configuration.
