Enhancement of (BH)max in a hard-soft-ferrite nanocomposite using exchange spring mechanism.

We have observed the exchange spring behavior in the soft (Fe3O4)-hard (BaCa2Fe16O27)-ferrite composite by tailoring the particle size of the individual phases and by suitable thermal treatment of the composite. The magnetization curve for the nanocomposite heated at 800 °C shows a single loop hysteresis showing the existence of the exchange spring phenomena in the composite and an enhancement of 13% in (BH)max compared to the parent hard ferrite (BaCa2Fe16O27). The Henkel plot provides the proof of the presence of the exchange interaction between the soft and hard grains as well as its dominance over the dipolar interaction in the nanocomposite. [ABSTRACT FROM AUTHOR]