Effects of seed layer on the coercivity and exchange bias in Co/Ag/CoO heterostructures

Magnetic multilayers of the form Co/Ag/CoO, grown on Si 3 N 4 substrates, with seed layers of Ag or Ta of various thicknesses were studied. There is a dramatic difference between the exchange fields and between the coercive fields for the differing seed layers such that, for a Ag seed layer, the loop can be fully shifted to one side of zero field whereas, with a Ta seed layer, this behavior is not observed. One important difference in the seed layers is the layer roughness; the Ag seed layer is as much as six times rougher than the Ta layer, as determined by atomic force microscopy.