The effect of nonmagnetic dilution in metallic antiferromagnets (AFMs) on the exchange bias (EB) has been investigated from a structural, magnetic, and Monte Carlo simulation point of view in bilayers of $\mathrm{CoFe}/(\mathrm{IrMn}{)}_{1-x}{\mathrm{Cu}}_x$. Dilution by Cu atoms throughout the volume of the AFM IrMn gives rise to an enhanced EB field ($H_{\mathrm{EB}}$) for $5\mathrm{K}\le T\le 350\mathrm{K}$. The thermoremanent magnetization of the sole AFM layer is also enhanced with dilution, shows qualitatively the same temperature dependence as $H_{\mathrm{EB}}$, and is at the origin of the EB mechanism. Monte Carlo simulations based on a Heisenberg model and temperature dependent uncompensated AFM moments confirm well the experimental results.

• Received 23 December 2006

DOI:https://doi.org/10.1103/PhysRevLett.99.097206