A nanogranular CoCoOAg system (with core-shell∕matrix structure), synthesized by reactive cosputtering, has been subjected to thermal treatments at progressively higher temperatures. The exchange-bias onset temperature increases in close correlation with the average superparamagnetic blocking temperature of the magnetic particles. This behavior, together with the nonmonotonic evolution of the exchange-bias field, is explained in terms of two structural relaxation processes previously characterized in simple CoAg granular alloys: (i) segregation of Co solute atoms from the Ag-rich matrix, and (ii) particle coarsening.

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