The Multiferroic Properties of Bi x FeO3 and Bi1−y Li y FeO3

Abstract

High-quality BiFeO3 films have been of great interest for magnetoelectric applications However the fabrication of BiFeO3 films with large remnant polarization and low leakage current is still rather difficult. In this work, BiFeO3-based composite films with different Bi content (BixFeO3, 0.7 ≤ x ≤ 1.3) were prepared by pulsed laser position on (001) SrTiO3 substrates with LaNiO3 as buffer layer. The dependence of their structure, ferroelectric properties, and exchange bias with NiFe layer on Bi content has been systematically investigated X-ray diffraction patterns show that all films have high (001) orientation, while Bi2O3 impurity can be observed in BixFeO3 with x ≥ 1.1. Clear ferroelectric hysteresis loops can be observed with x > 0.9. The ferroelectric properties have been further improved by Li doping with concentration of 0.03 to suppress the leakage current due to its p-type doping which can compensate the intrinsic n-type conduction. Exchange bias has been observed in all the films with a 3.6-nm-thick NiFe layer The exchange bias field decreases with increasing Bi concentration, but increases by Li doping with concentrations of 0.03 and 0.05.