Rationalizing strain engineering effects in rare-earth nickelates

The physics of nickel perovskites is richwith various competing electronic phases that can be tuned by chemical or external degrees of freedom. As such, nickelates show strong potential for oxide electronics devices based on strongly correlated systems. However, their complexity has hitherto challenged a detailed understanding of classical material engineering effects using, e. g., epitaxial strain. Here we investigate this important pending issue by comparing experimental data with results from first-principles calculations using the Heyd-Scuseria-Ernzerhof hybrid exchange-correlation functional. The theory properly describes the magnetic ground state as well as the preferred orbital occupation observed by x-ray linear dichroism. It also shows that the strain-induced modulation of the metal-to-insulator transition temperature is likely driven by changes in the bandwidth, rather than by the charge-transfer energy.