When a weak magnetic field, such as that from a bit on a hard disk, passes beneath such a structure, the magnetic orientation of the unpinned magnetic layer rotates relative to that of the pinned layer, generating a significant change in electrical resistance due to the GMR effect. This structure was named the spin valve. To see an animation of how MR and GMR recording heads work, click here . Gurney and colleagues worked for several years to perfect the sensor design that is used in the new disk drives. IBM's intensive studies of GMR enabled us to enhance considerably the performance of some low-field sensors.
Electrical resistance is due to scattering of electrons within a material.
By analogy, consider how fast it takes you to drive from one town to another. Without obstacles on a freeway, you can proceed quickly. But if you encounter heavy traffice, accidents, road construction and other obstacles, you'll travel much slower. For an animation showing how electrons of different spins scatter within a GMR structure, click here . We've just explained our astounding new technological achievement and announced our new 16.8 Gigabyte product.