Crossover between distinct symmetries in solid solutions of rare earth nickelates

A strong coupling of the lattice to functional properties is observed in many transition metal oxide systems such as the ABO3 perovskites. In the quest for tailor-made materials it is essential to be able to control the structural properties of the compound(s) of interest. Here, thin film solid solutions that combine NdNiO3 and LaNiO3, two materials with perovskite structure but distinct space-groups, are analyzed. Raman spectroscopy and scanning transmission electron microscopy are combined in a synergistic approach to fully determine the mechanism of the structural crossover with chemical composition. It is found that the symmetry transition is achieved by phase coexistence in a way that depends upon the substrate selected. These results carry implications for analog-tuning of physical properties in future functional materials based on these compounds.

摘要