Dimension effect on the in-depth phase transition of MnAs/GaAs(001): From a thin film to a nanorod

We explore the dimension effect on the in-depth phase transition behavior of MnAs thin films on GaAs substrate by investigating the in-depth strain distribution with experiments and simulations. The strain distribution along the film growth direction is verified to be changed when a two-dimensional thin film is thinned into a one-dimensional nanorod as a cross-section transmission electron microscopy (TEM) specimen, thus resulting in a significantly different transition behavior. Our work brings more insights into the transition mechanism of MnAs thin films and illustrates a noteworthy issue in TEM studies of the phase transition at the interface of epitaxial thin films.