Exchange bias effect and exchange spring-type behavior of core-shell structured MnFe

In this article, we have explored the exchange coupled behavior of MnFe2O4/α-Fe2O3 core-shell based nanocomposite systems. Four nanocomposite samples were prepared by varying weight percentage of α-Fe2O3 with the generic formula (1 − x) MnFe2O4/x α-Fe2O3 (x = 0.15, 0.30, 0.45 and 0.60). The existence of single spinel cubic phase of MnFe2O4 along with rhombohedral phase of α-Fe2O3 was verified by the X-ray powder diffraction profiles. The FC hysteresis loops disclosed a large amount of exchange bias (HEB) of 1.1 kOe along with high coercivity (3.3 kOe) at 5 K for all the samples. Exchange spring type behavior was observed in hysteresis curves of entire nanocomposites. The M-T plots revealed that the blocking temperature (TB) of entire samples was above the room temperature together with presence of strong interparticle interactions. The blocking temperature was found to shift above 300 K even in tiny size due to significant exchange bias effect