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.