Universal angular magnetoresistance and spin torque in   ferromagnetic/normal metal hybrids
  The electrical resistance of ferromagnetic/normal-metal (F/N) heterostructures depends on the nature of the junctions which may be tunnel barriers, point contacts, or intermetallic interfaces. For all junction types, the resistance of disordered F/N/F perpendicular spin valves as a function of the angle between magnetization vectors is shown to obey a simple universal law. The spin-current induced magnetization torque can be measured by the angular magnetoresistance of these spin valves. The results are generalized to arbitrary magnetoelectronic circuits. 
Gerrit E. W. Bauer, Yaroslav Tserkovnyak, Daniel Huertas-Hernando, and   Arne Brataas