Structure, ferroelectric/magnetoelectric properties and leakage current density of (Bi0.85Nd0.15)FeO3 thin films

In this paper, we report on the structure, ferroelectric/magnetoelectric properties and improvement of leakage current density of (Bi0.85Nd0.15)FeO3 (BNFO) thin films deposited on Pt(1 1 1)/Ti/SiO2/Si substrates from the polymeric precursor method. X-ray patterns and Rietveld refinement indicated that BNFO thin films with a tetragonal structure can be obtained at 500 °C for 2 h in static air. Field emission scanning electron, atomic force and piezoelectric force microscopies showed the microstructure, thickness and domains with polarization-oriented vectors of BNFO thin films. Ferroelectric and magnetoelectric properties are evident by hysteresis loops. The magnetoelectric coefficient measurement was performed to show the magnetoelectric coupling behavior. The maximum magnetoelectric coefficient in the longitudinal direction was close to 12 V/cm Oe. Piezoresponse force microscopy micrographs reveal a polarization reversal with 71° and 180° domain switchings and one striped-domain pattern oriented at 45° besides the presence of some nanodomains with rhombohedral phase involved in a matrix with tetragonal structure. The cluster models illustrated the unipolar strain behavior of BNFO thin films. The leakage current density at 5.0 V is equal to 1.5 × 10−10 A/cm2 and the dominant mechanism in the low-leakage current for BNFO thin films was space-charge-limited conduction.

Rietveld refinement plot of the (Bi0.85Nd0.15)FeO3 (BNFO) film/Pt(1 1 1) substrate and inset shows the [PtO12] clusters for the Pt-substrate and supercells (1 × 2 × 2) for BNFO film with three type of clusters: [BiO12], [NdO12] and [FeO6].Figure optionsDownload as PowerPoint slideResearch highlights
► New model (supercell) for structure tetragonal with clusters, ferroelectric/magnetoelectric properties and improved leakage current density of (Bi0.85Nd0.15)FeO3 (BNFO) thin films.
► Unipolar strain behavior and piezoelectric force microscopy (PFM) of BNFO thin films explained in details.
► Polarization reversal indicated two types of domain behavior in 71° and 180° domain switchings and one striped-domain pattern oriented at 45° in the PFM micrographs reveals the presence of some nanodomains with rhombohedral phase in a matrix globally with tetragonal structure.