Physical properties of Cr-doped epitaxial BiFeO3 thin films influenced by ferroelectric domain structures

Abstract

We investigated the physical properties of Cr-doped epitaxial BiFeO3 (CBFO) thin films influenced by ferroelectric domain structures. The epitaxial CBFO thin films with Cr concentrations of 0, 2, 4, 6, and 8% were deposited on Nb-doped single crystal SrTiO3 substrates by pulsed laser deposition. The epitaxial CBFO thin films with Cr concentrations of 0, 2, and 4% had highly c-oriented crystallinity and the epitaxial CBFO thin films with Cr concentrations of 6% and 8% exhibited mixed crystallinity of c-oriented crystallinity and (101)-oriented crystallinity. The CBFO thin film with a Cr concentration of 4% showed the highest ferroelectric polarization, and the ferroelectric polarizations of the CBFO thin films with a Cr concentration of more than 4% were reduced by the formation of (101)-oriented grains. On the other hand, the piezoelectric properties, leakage current characteristics, and ferromagnetic properties of CBFO thin films were simultaneously improved by increasing the Cr concentration. Terraces indicating layer-by-layer growth were observed on the surface of the CBFO thin films, and the edges of the terraces formed on the surface of the CBFO thin films were blurred when the Cr concentration increased. The ferroelectric domain structures of the CBFO thin films observed with a piezoelectric response microscope changed from a stripe domain structure to a mosaic domain structure when the Cr concentration exceeded 6%.