Cracks in Magnetic Nanocrystal Films: Do Directional and Isotropic Crack Patterns Follow the Same Scaling Law?

In this letter, we show that the use of nanocrystals enables new insights into the scaling law of crack patterns. Directional and isotropic crack patterns made of gamma-Fe2O3 nanocrystals follow the same scaling law, with the film height varying by 3 orders of magnitude. A simple two-dimensional computer model for elastic fracture also leads to the same scaling behavior for directional and isotropic cracks, in good agreement with the experiments.