Flexible and self-standing nickel ferrite–PVDF-TrFE cast films: promising candidates for high-end magnetoelectric applications

Abstract

Polymer-based magnetoelectrics are identified as a newly emerging area of research due to their profound potential applications centered on spintronic technology. In line with this, we have developed a novel, flexible nickel ferrite (NiFe₂O₄)–PVDF-TrFE (NF–PVDF-TrFE) polymer based magnetoelectric film, with excellent magnetoelectric coupling at room temperature. Nanocomposite films were prepared by the solution cast method, in which the nickel ferrite nanoparticles with different weight percentages (2, 4, 8 and 16%) were incorporated in the electroactive PVDF-TrFE polymer matrix. The ferroelectric β-crystalline phase of PVDF-TrFE was confirmed by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and Raman studies. Dielectric and thermal properties of the composite films were found to be substantially improved with the addition of magnetic nanoparticles. Ferroelectric and magnetic characteristics of the composite films were also considerably improved with an increase in NiFe₂O₄ concentration. A magnetic saturation (M_s) of 4.81 emu g⁻¹ and a ferroelectric maximum polarization of 18.9 μC cm⁻² were shown by the composite film at room temperature for 16 wt% loading of NF nanoparticles. Besides these functionalities, ac and dc magnetoelectric coupling coefficients of 69 mV cm⁻¹ Oe⁻¹ and 90 mV cm⁻¹ Oe⁻¹ were obtained for 16NF–PVDF-TrFE along with excellent mechanical stability. These flexible and self-standing magnetoelectric composite films with enhanced magnetoelectric coupling coefficients at room temperature could be suitable candidates for the development of ultramodern information storage devices, memory devices, signal processing devices etc.