Multiferroic properties of NiFe₂O₄-Ba_0.7Ca_0.3TiO₃ nanocomposites

Abstract In this report, we present results on the multiferroic properties of four nanocomposite samples of NiFe 2 O 4 -Ba 0.7 Ca 0.3 TiO 3 (NFO/BCTO), which were fabricated through combinations of high-energy ball milling, heat treatment, and spark plasma sintering techniques. Structural analyses revealed that these samples simultaneously contain two phases of nano-sized NiFe 2 O 4 (NFO) and Ba 0.7 Ca 0.3 TiO 3 (BCTO) crystals. The addition of NFO into the BCTO-host did not alter the crystal structure but significantly improved the multiferroic characteristics compared to pure BCTO. Furthermore, variations in saturation magnetization ( M s ) and coercivity ( H c ) were investigated as a function of temperature. The results showed that Ms increased gradually with the concentration of NFO. In terms of temperature dependence, M s ( T ) data deviated from the Bloch’s law with an exponent coefficient α changing in the range of 1.8–1.9, decreasing gradually as the NFO concentration increased. Meanwhile, H c decreased gradually as the NFO concentration increased and followed the Kneller’s law in terms of temperature dependence.