This phenomenon is where weak changes in magnetic resistance give rise to big differences in electrical resistance. This is one of the core principles that allows for the development of sensitive reading tools for retrieving magnetically sorted data in devices from computers to portable media players.
The Nobel Foundation regards Fert and Grunberg's accomplishment as "one of the first major applications of nanotechnology."
BBC News quotes Professor Ben Murdin of the University of Surrey, UK, as saying, “Without [giant magnetoresistance] you would not be able to store more than one song on your iPod!" Murdin went on to tell BBC News, “A computer hard-disk reader that uses a GMR sensor is equivalent to a jet flying at a speed of 30,000 kmps, at a height of just one metre above the ground, and yet being able to see and catalogue every single blade of grass it passes over."
American Stuart Parkin developed the industrial process that made the theory into your high-density hard disk drive, and deserves a great deal of credit as well. Congratulations to all. Now get busy on cheap flash memory, will you?