Piezoresponse Force Microscopy Studies of pc-BiFeO 3 Thin Films Produced by the Simultaneous Laser Ablation of Bi and Fe
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Piezoresponse Force Microscopy Studies of pc-BiFeO3 Thin Films Produced by the Simultaneous Laser Ablation of Bi and FeO3 C. I. Enriquez-Flores1, J. J. Gervacio-Arciniega1, F. J. Flores-Ruiz1, D. Cardona2, E. Camps2, J. Muñoz-Saldaña1 and F.J. Espinoza-Beltrán1 1
CINVESTAV Unidad Querétaro, Lib. Norponiente 2000, Fracc. Real de Juriquilla, Querétaro, Qro., Mexico, 2
Departamento de Física, Instituto Nacional de Investigaciones Nucleares, Apdo. Postal 18-1027, Mexico D.F., CP 11801, Mexico.
ABSTRACT Bismuth iron oxide BFO films were produced by the pulsed laser deposition technique. These films are a mixture of BiFeO3 ferroelectrical and Bi25 FeO40 piezoelectrical phases. The ferroelectrical domain structure of these films was studied via contact resonance piezoresponse force microscopy (CR-PFM) and resonance tracking PFM (RT-PFM). The proportions of area of these BFO phases were derived from the PFM images. The ferroelectrical domain size corresponds to the size of the BiFeO3 crystals. The CR-PFM and RT-PFM techniques allowed us to be able to distinguish between the ferroelectric domains and the piezoelectric regions existing in the polycrystalline films.
INTRODUCTION The scientific community has a lot of interest in multiferroic materials due to their attractive simultaneous magnetic and ferroelectric properties. BiFeO3 is one of the most studied multiferroic materials due to its good ferroelectric properties with a Curie temperature T C ≈ 830.8 ºC and antiferromagnetic characteristics with a Néel temperature TN ≈ 310.8 ºC [1-3]. Pulsed laser deposition (PLD) is one of the most popular techniques used to produce BiFO 3 films. With the PLD method, thin films can be prepared by the ablation of one or more targets illuminated by a focused pulsed-laser beam. This technique was first used for the preparation of semiconductors and dielectric thin films. Some characteristics of PLD are well known, namely the stoichiometry transfer between target and deposited film, the high deposition rates of about 0.1 nm per pulse and the occurrence of droplets on the substrate surface. This deposition technique has been intensively used for all kinds of materials including oxides, nitrides, carbides, and also for preparing metallic systems and even organic materials such as polymers and fullerenes [4]. The ferroelectric and ferromagnetic properties of BFO films produced by the PLD technique depend on the crystalline phases, which exist in the films, so it is important to know the microstructure. In this work we combine X-ray diffraction with CR-PFM and RT-PFM measurements to characterize BFO films deposited by PLD in order to study the configuration of the ferroelectric domains and the effect of the deposition parameters.
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EXPERIMENT A schematic setup of the CR-PFM [4-9] and RT-PFM methods are shown in Figure 1a. and 1b. These methods are performed in contact mode, with the sample and the tip of the probe being in contact, while the probe is vibrating in a flexural resonance frequency (for CR-PFM) or sweeping in a range of frequenc
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