Bruce Gurney did pioneering work towards developing a room-temperature version of this phenomenon, while Xiao and Berkowiez independently discovered a type of this phenomenon in granular Cobalt-Copper solids. One version of it can be understood in terms of RKKY coupling, while devices which exploit a namesake type of this effect come in CPP and CIP varieties, and are known as spin valves. One version of this phenomenon is a result of spin-dependent electron scattering, and was discovered in Iron-Chromium-Iron multilayers by Albert Fert and Peter Grunberg in 1988. For 10 points, identify this effect in which a metal's conductivity is altered in the presence of a magnetic field and whose "giant" variety led to the 2007 Nobel in Physics, and which is commonly used in 
Bruce Gurney did pioneering work towards developing a room-temperature version of this phenomenon, while Xiao and Berkowiez independently discovered a type of this phenomenon in granular Cobalt-Copper solids. One version of it can be understood in terms of RKKY coupling, while devices which exploit a namesake type of this effect come in CPP and CIP varieties, and are known as spin valves. One version of this phenomenon is a result of spin-dependent electron scattering, and was discovered in Iron-Chromium-Iron multilayers by Albert Fert and Peter Grunberg in 1988. For 10 points, identify this effect in which a metal's conductivity is altered in the presence of a magnetic field and whose "giant" variety led to the 2007 Nobel in Physics, and which is commonly used in read-out heads in hard drives.
Bruce Gurney did pioneering work towards developing a room-temperature version of this phenomenon, while Xiao and Berkowiez independently discovered a type of this phenomenon in granular Cobalt-Copper solids.
Magnetoresistance [accept Giant Magnetoresistance or GMR]