Oscillatory magnetic exchange coupling through thin copper layers

Confirming theoretical predictions more than 25 years old, we show that Co slabs are indirectly exchange coupled via thin Cu layers with a coupling that alternates back and forth between antiferromagnetic and ferromagnetic. Four oscillations are observed with a period of 10. Moreover, the antiferromagnetically coupled Co/Cu superlattices exhibit extraordinarily large saturation magnetoresistances at 300 K of more than 65%.