Epitaxial LaFeO3/SrTiO3 films before and after irradiation

Sample Preparation: Thin films of LaFeO3 (LFO) were epitaxially grown approximately 10-15 nm thick on (001)-oriented SrTiO3 (STO) by two methods: pulsed laser deposition (PLD) and molecular beam epitaxy (MBE). PLD films were grown in such a way as to incorporate vertical defect domains. Films were irradiated to a damage level of 0.1 displacements per atom (dpa) (3.74×1013 ions/cm2) at nominally room temperature with 2.8 MeV Au2+ at 3° off normal to minimize channeling effects and a flux of approximately 3.7×1011 ions/cm2/sec. Dose was calculated using the Stopping Range of Ions in Matter (SRIM-2013) Monte Carlo approach to replicate experimental conditions and ensure the Au implantation peak was within the substrate. A mask was used to cover sections of the films during irradiation to maintain pristine portions.STEM/EDS Measurements: Lamellae from each region (0 and 0.1 dpa) from both films (PLD and MBE grown) were extracted by standard focused ion beam (FIB) procedures and examined by scanning transmission electron microscopy (STEM) imaging and energy dispersive X-ray spectroscopy (EDS). Imaging and spectroscopy were conducted on a probe-corrected 300 kV Thermofisher Themis Z with a beam convergence of 18 mrad and a collection angle range of 50 to 200 mrad (for the HAADF detector). A dwell time of 2 μs was used to collect spectra in 512×512 arrays for EDS mapping, resulting in pixel sizes between 35-71 pm.