2, Auburn University, Auburn, Alabama, United States
Thin film synthesis methods developed over the past decades have unlocked emergent interface properties ranging from conductivity to ferroelectricity. However, our attempts to exercise control over interfaces are constrained by a limited understanding of growth pathways and kinetics, as well as by imprecise probes of local electronic structure. Here we examine the rearrangement of atomic planes at a polar / non-polar junction of LaFeO3 (LFO) / n-SrTiO3 (STO) using aberration-corrected scanning transmission electron microscopy (STEM) and electron energy-loss spectroscopy (STEM-EELS). While surface characterization confirms that substrates with two different (TiO2 and SrO) terminations were prepared prior to LFO deposition, STEM-EELS measurements of the final heterojunctions reveal a predominantly LaO / TiO2 interface configuration in both cases. Furthermore, we observe a reduction in the Fe L23 edge that points toward possible interfacial conductivity. From ab initio simulations, we discuss several possible routes for the apparent disappearance of the FeO2 / SrO interface. Our results illustrate how advanced characterization coupled with judicious control of deposition parameters may be used to map growth pathways, opening new avenues to control the structure and properties of functional interfacial systems.