Co layer thickness dependence of exchange biasing for IrMn/Co and FeMn/Co

We present a high resolution study of the ferromagnetic layer thickness dependence of exchange bias field (H-EB) and coercivity (H-C) in IrMn/Co and FeMn/Co bilayers using the magneto-optical Kerr effect. Samples are sputtered wedges on silicon with Co thicknesses ranging from 1 to 17 nm. The IrMn/Co (with exchange bias interface energy of similar to0.14 erg/cm(2)) shows square loops, a smooth increase in H-EB with inverse thickness, and a complicated behavior for coercivity, perhaps due to competition with thickness dependent coercive mechanisms. The FeMn/Co (with exchange bias interface energy of similar to0.059 erg/cm(2)) shows more rounded loops, a plateau of H-EB with decreasing thickness, and a smooth increase in coercivity with inverse thickness. (C) 2003 American Institute of Physics.