We report that epitaxial Sr2IrO4 thin-films can be selectively grown using pulsed laser deposition (PLD). Due to the competition between the Ruddlesden-Popper phases of strontium iridates (Srn+1IrnO3n+1), conventional PLD methods often result in mixed phases of Sr2IrO4 (n = 1), Sr3Ir2O7 (n = 2), and SrIrO3 (n = ∞). We have discovered that reduced PLD plume dimensions and slow deposition rates are the key for stabilizing pure Sr2IrO4 phase thin-films, identified by real-time in-situ monitoring of their optical spectra. The slow film deposition results in a thermodynamically stable TiO2\\SrO\IrO2\SrO\SrO configuration at an interface rather than TiO2\\SrO\SrO\IrO2\SrO between a TiO2-terminated SrTiO3 substrate and a Sr2IrO4 thin film, which is consistent with other layered oxides grown by molecular beam epitaxy. Our approach provides an effective method for using PLD to achieve pure phase thin-films of layered materials that are susceptible to several energetically competing phases.
Digital Object Identifier (DOI)
We acknowledge the support of National Science Foundation Grant No. DMR-1454200 for sample synthesis and characterizations.
See supplementary material for a photograph of focused laser beam spot images and in-situ optical spectra of a STO substrate at 700 °C and room temperature.
Seo, Sung S. Ambrose; Nichols, J.; Hwang, J.; Terzic, Jsaminka; Gruenewald, John H.; Souri, Maryam; Thompson, Justin K.; Connell, John G.; and Cao, Gang, "Selective Growth of Epitaxial Sr2IrO4 by Controlling Plume Dimensions in Pulsed Laser Deposition" (2016). Physics and Astronomy Faculty Publications. 477.