Electric field poling induced self-biased converse magnetoelectric response in PMN-PT/NiFe₂O₄ nanocomposites

In this letter, studies on structural transitions and the effect of electric field poling on magnetoelectric (ME) properties in 0.65Pb (Mg_1/3Nb_2/3)O₃-0.35PbTiO₃ (PMN-PT)/NiFe₂O₄ (NFO) nanocomposites are reported. The composite illustrates dramatic changes in the NFO crystal structure across ferroelectric transition temperature [Curie temperature (T_c) ∼ 450 K] of PMN-PT, while pure NFO does not exhibit any structural change in the temperature range (300 K–650 K). Synchrotron based X-ray diffraction analysis revealed the splitting of NFO peaks across the T_c of PMN-PT in the PMN-PT/NFO composite. Consequently, the anomalies are observed in temperature dependent magnetization of the NFO phase at the T_c of PMN-PT, establishing ME coupling in the PMN-PT/NFO composite. Furthermore, the composite exhibits drastic modification in ME coupling under electrically poled and unpoled conditions. A large self-biased ME effect characterized by non-zero ME response at zero H_bias was observed in electrically poled composites, which was not observed in unpoled PMN-PT/NFO. These results propose an alternative mechanism for intrinsic converse ME effects. The maximum magnetoelectric output was doubled after electrical poling. The observed self-biased converse magnetoelectric effect at room temperature provides potential applications in electrically controlled memory devices and magnetic flux control devices.