Disentangling lattice and electronic contributions to the metal-insulator transition from bulk vs. layer confined RNiO3

Our combined theoretical and experimental study of bulk and heterostructured forms of a correlated electron material leads to insights into the metal-insulator transition. Comparison of single-layer, bilayer, and very thick samples validates a combined ab-initio/many-body theoretical approach and enables a clear disentangling of electronic and lattice contributions to the transition by independently changing each. Analysis of the lattice relaxations associated with the metal-insulator transition highlights the importance of the elastic properties of and propagation of distortions into the electronically inert counterlayer, defining a control parameter for tuning electronic properties. Counterlayer-induced bond-angle changes and electronic confinement provide separate tuning parameters, with bond-angle changes found to be a much less effective tuning parameter.