Enhancement of ferroelectric properties of the Ga0.6Fe1.4O3 films by Zn,N co-doping

Abstract

Multiferroic materials have attracted considerable interests due to their scientific and technological importance in advanced devices. Ga0.6Fe1.4O3 thin film exhibits ferrimagnetism above room temperature but suffers from large leakage current. To reduce the charge conduction and enhance the ferroelectric properties of Ga0.6Fe1.4O3 film, ion doping is a useful technique. In this study, we fabricated Ga0.6Fe1.4-xZnxO3/N films by substituting Zn2+ and N3- ions in Ga0.6Fe1.4O3 for Fe and O, respectively. The influence of Zn, N co-doping on the structure, leakage current, magnetic and ferroelectric properties of the films were investigated. The results indicated that the films exhibited the orthorhombic structure with the incorporation of Zn and N. All Ga0.6Fe1.4-xZnxO3/N films showed above room temperature ferrimagnetism, and the magnetization and transition temperature values decreased with Zn,N co-doping. The microscopic and macroscopic ferroelectric measurements have demonstrated the ferroelectric polarization switching of the films. The ferroelectric hysteresis loops of the Ga0.6Fe1.38Zn0.02O3/N film showed the remnant polarization of ∼0.46 μC/cm2 with the coercive field of ±2 V at room temperature. The leakage current significantly reduced from ∼3.27×10−1 A/cm2 for pure Ga0.6Fe1.4O3 film to ∼1.48×10−5 A/cm2 for Ga0.6Fe1.35Zn0.05O3/N film, by four orders of magnitude. This may be attributed to the incorporation of Zn2+ and N3-, providing charge compensation to valence fluctuations of Fe between Fe3+ and Fe2+. These results provide an effective method to improve the ferroelectricity of Ga0.6Fe1.4O3 film, and open a wide perspective for the potential application in magnetoelectric devices.