Effect of thin oxide capping on interlayer coupling in spin valves

We controlled interlayer coupling from ferromagnetic to antiferromagnetic b y appropriately capping spin valves with thin oxides. The interlayer coupli ng field was -16.6 Oe at a Cu-spacer thickness of 30 Angstrom. The sign of coupling changed at a Cu-spacer thickness of 20 Angstrom. The antiferromagn etic coupling achieved in this way allowed a reduction of thickness of the Cu spacer down to 20 Angstrom without loss of good magnetic and electrical properties, and this led to a significant improvement in the MR response of the spin valves. The interlayer coupling field was only +8.6 Oe even at a Cu-spacer thickness of 20 Angstrom. We attribute the improvement in MR resp onse to less current shunting through the most conductive Cu layer and to e nhanced specular scattering at the interface between the free and the oxide capping layer.