Structural, electrical, and magnetic properties of multiferroic Bi1−xGdxFe0.97Co0.03O3 thin films

Single-phase Bi1−xGdxFe0.97Co0.03O3 (BGFC, x = 0.04-0.16) thin films were successfully synthesized by using a chemical solution deposition method. The BGFC thin films exhibit a series of structural phase transitions as a function of Gd composition, accompanied by dramatic changes in the ferroelectric, leakage current and dielectric properties. It has been demonstrated that Gd doping at Bi-site can monotonously decrease the remanent magnetization, mainly due to the gradual decrease in Fe2+ content. Weak compress stress favors the ferromagnetism in the BGFC (x = 0.08) thin film, which takes a maximum saturation magnetization of 13.2 emu/cm3 with the smallest coercivity of 120 Oe. At particular composition of x = 0.12, the film exhibits rectangular hysteresis loop and sharp polarization current curve, a giant remanent polarization of 101 μC/cm2 and a small coercive field of 345 kV/cm is observed. This paper reports that rare earth driven ferroelectric to antiferroelectric (AFE) phase transition can be obtained at room temperature in the binary elements codoped BFO thin films. Besides, the defect polarization serves approximatively as the AFE domains blocking the ferroelectric switching.