Columnar Growth of BiFeO3 Films Prepared by Magnetic-field-assisted Pulsed Laser Deposition

Abstract

Polycrystalline BiFeO3 (BFO) films have been prepared by using magnetic-field-assisted pulsed laser deposition (PLD), and the microstructure and ferroelectric properties have been investigated. A high deposition rate has been achieved, and a columnar structure has been observed in comparison with that of a BFO thin film prepared without a magnetic field. Trajectories of the charged particles in the plume under a magnetic field have been calculated. As a result, the angle between the substrate normal and the incident particle on the substrate becomes large in magnetic-field-assisted PLD. The evolution of film growth in PLD under a magnetic field has been analyzed by the calculation using the facet growth model. The calculation results show the film with the columnar structure normal to the substrate is obtained. In the experiments, the plume is confined by a magnetic field, and its emission intensity becomes high in PLD under a magnetic field. Moreover, the evaporated ions are excited more strongly under a magnetic field than without a magnetic field. The BFO films show the columnar structure that coincides well with the calculated image, and the deposition rate is enhanced. The polarization versus electric field (P – E) hysteresis loops of BFO films is obtained at room temperature (RT), and the polarization is reduced in the film deposited under a magnetic field.