Original: In 1988 Fert discovered the Giant magnetoresistance effect (GMR) in multilayers of iron and chromium which is recognized as the birth of spintronics; GMR was simultaneously and independently discovered by Peter Grünberg from the Jülich Research Centre.
Simplified: In 1988 Fert discovered Giant magnetoresistance (GMR) in iron and chromium which began spintronics; GMR was also discovered by Peter Grünberg from the Jülich Research Centre but Peter Grünberg did not work with Professor Fert.