Dilution dependence of blocking temperature distribution in the exchange bias system CoO(111)/Co(111)

In epitaxially grown CoO(111)/Co(111) bilayers we have determined the blocking temperature distribution f(Tb), which is correlated with the antiferromagnetic domain size (z) distribution f(z). The latter is probed by reversing antiferromagnetic domains at successively higher temperatures in the reversed cooling field. The implementation of nonmagnetic defects throughout the antiferromagnet CoO is found to give rise to a broadening of the domain size distribution f(z) within CoO as evidenced by a broadened f(Tb). This broadening is responsible for an enhancement of the exchange bias field.