Ferroelectric domain structures and thickness scaling of epitaxial BiFeO3 thin films

• Ferroelectric domain structures of epitaxial (001) and (111) BFO thin films.
• Stripe and mosaic ferroelectric domain structures.
• The scaling law of Landau, Lifshitz and Kittel for ferroelectric domain size vs. film thickness.

We report the ferroelectric properties of the epitaxial BiFeO3 (BFO) thin films grown on Nb-doped SrTiO3 substrates. The (001) and (111) BFO thin films were grown epitaxially on a single-crystalline (100) and (111) Nb-doped SrTiO3 substrate by pulse laser deposition, respectively. The (111) BFO film gave higher remnant polarization in the ferroelectric hysteresis loop than that of the (001) film. The (001) and (111) BFO films revealed striped and mosaic ferroelectric domain structures, respectively. The ferroelectric domain size vs. film thickness was in accordance with the scaling law of Landau, Lifshitz and Kittel. The domains of the (001) BFO film were larger than those of the (111) BFO film. This is because the (111) BFO film has a relatively large remnant polarization, even though the (111) film has a lower domain wall energy.