Temperature-induced strain mediated magnetization changes in NiFe2O4/BaTiO3 heterostructure

Herein, we report the temperature-induced magnetization changes of NiFe2O4 thin film, which is coated over a ferroelectric BaTiO3 ceramic substrate. The solid-state reaction method was adopted for the preparation of ferroelectric BaTiO3 (BT) substrate, whereas NiFe2O4 (NFO) film was deposited by spin-coating method. Rietveld refinement revealed that BT substrate has a tetragonal (P4mm) crystal system along with a minor orthorhombic phase (Amm2) at room temperature. The GIXRD analysis confirms the phase purity of NFO/BT heterostructure. Polarization hysteresis with respect to electric field (P-E loop) and the temperature-dependent dielectric measurement of BT substrate demonstrate its typical ferroelectric and phase transition behavior, respectively. Magnetization hysteresis loops were recorded for the NFO/BT heterostructure at 150, 240 and 300 K. A significant increase in the remnant magnetization (MR) and coercive field (HC) of NFO film are noticed while cooling the heterostructure below 300 K. Variation in the magnetization of NFO film corresponds to the change in the structural phase transition (Amm2 at 240 K and R3c at 150 K) of BT while cooling below RT. The interfacial strain mediated coupling is the primary mechanism attributed to the temperature-induced changes in the magnetization of NFO/BT heterostructure.