Isostructural phase transitions in GaN/ScN and InN/ScN superlattices

We predict the existence of pressure-induced isostructural phase transitions (IPTs) in GaN/ScN and InN/ScN superlattices from first principles. The IPTs in these superlattices are anomalous in the sense that they are associated with trivial order parameters and generate a dramatic change in many physical quantities. Furthermore, the {\it order} of the phase transition is found to be dependent on the superlattice period and on the non-transition-metal cation. We also reveal the reason behind, and consequences of, these unusual dependencies and IPTs.