Thermodynamic guiding principles in selective synthesis of strontium iridate Ruddlesden-Popper epitaxial films

We demonstrate the selective fabrication of Ruddlesden-Popper (RP) type SrIrO3, Sr3Ir2O7, and Sr2IrO4 epitaxial thin films from a single SrIrO3 target using pulsed laser deposition (PLD). We identified that the growth conditions stabilizing each phase directly map onto the phase diagram expected from thermodynamic equilibria. This approach allows precise cation stoichiometry control as evidenced by the stabilization of single phase Sr3Ir2O7 for the first time, overcoming the close thermodynamic stability between neighboring RP phases. Despite the non-equilibrium nature of PLD, these results highlight the importance of thermodynamic guiding principles to strategically synthesize the targeted phase in complex oxide thin films.