#Epitaxial antiperovskite/perovskite heterostructures for materials design

To understand the structure and chemical composition of the Mn₃GaN/LSAT interface, Quintela et al. combined atomic-resolution scanning transmission electron microscopy (STEM) with electron energy-loss spectroscopy (EELS) and energy-dispersive X-ray spectroscopy (EDS). The first interfacial Mn₃GaN monolayer showed a pattern of alternating bright and dark spots to indicate compositional or structural reconfiguration at the interface. Using simulations and structural chemical analyses, the team showed transitions from the LSAT substrate to the Mn₃GaN film mediated through a sharp interfacial monolayer. To determine the atomic structure of this interfacial monolayer, Quintela et al. performed additional STEM and EDS studies and showed the ordering of atoms in a two-dimensional (2-D) periodic structure with rotational symmetry.
First-principles calculations
The team performed first-principles calculations to study the stability of the interfacial model derived from atomic resolution experiments. Using simulations, they calculated the formation energies to test for stability and confirmed the interfacial model to be energetically stable. Additional work, however, showed apparent discrepancies between the experimental and theoretical studies, which the scientists credited to the onset of Mn₃GaN growth in the presence of an energy barrier, where the discrepancy prevented the system from relaxing from the local to the global energy minimum. Quintela et al. further explored this hypothesis in their work. The combined experimental and theoretical studies showed how the interfacial monolayer worked as a structural bridge between the perovskite substrate and antiperovskite film to establish heteroepitaxy between the nonisostructural (dissimilar crystal structure) materials with different chemical composition and binding.