Fractal dimension and size scaling of domains in thin films of multiferroic BiFeO3

TL;DR

This paper investigates the irregular, fractal-shaped ferroelectric domains in ultrathin BiFeO3 films, revealing unique size scaling behavior linked to their fractal nature, differing from typical ferroic domain patterns.

Contribution

It introduces a model connecting domain size in thin films to fractal dimension, highlighting novel domain morphology in BiFeO3.

Findings

Domains are irregular with fractal characteristics.

Domain size does not follow the typical square root scaling.

A new model links domain size to fractal dimension.

Abstract

We have analyzed the morphology of ferroelectric domains in very thin films of multiferroic BiFeO3. Unlike the more common stripe domains observed in thicker films BiFeO3 or in other ferroics, the domains tend not to be straight, but irregular in shape, with significant domain wall roughening leading to a fractal dimensionality. Also contrary to what is usually observed in other ferroics, the domain size appears not to scale as the square root of the film thickness. A model is proposed in which the observed domain size as a function of film thickness can be directly linked to the fractal dimension of the domains.