Supporting data for: Optical properties of electrochemically gated La1-xSrxCoO3-δ as a topotactic phase-change material

The data included here contain the information necessary to recreate the figures in a manuscript titled \"Optical Properties of Electrochemically Gated La1-xSrxCoO3-δ as a Topotactic Phase-Change Material\". The data files include scanning transmission electron microscopy (STEM) images of electrochemically gated La1-xSrxCoO3-δ (LSCO) films, finite-difference time-domain (FDTD)-simulated electric field and reflectance data for LSCO-based metasurfaces, transfer-matrix model reflectance data for LSCO films on gold substrates, complex refractive index data for LSCO films before and after electrochemical gating, electronic resistivity data for LSCO films before and after electrochemical gating, source-drain current measurements of LSCO films during electrochemical gating, and X-ray diffraction data for LSCO films before and after electrochemical gating., Methods for collection/generation of data:
Growth and Fabrication of LSCO Transistors: La1-xSrxCoO3-δ (LSCO) films with 0 ≤ x ≤ 0.70, along with brownmillerite-phase SrCoO2.5 (BM SCO) films (x = 1.00), were deposited on (LaAlO3)0.3(Sr2TaAlO6)0.7 (001) (LSAT) substrates using high-pressure-oxygen sputtering using previously-optimized conditions. First, 10 mm x 10 mm x 0.5 mm commercial LSAT(001) substrates from MTI were annealed at 900 °C under 1 Torr of ultra-high-purity (99.998%) O2 for 15 minutes. LSCO films with 0 ≤ x ≤ 0.70 were then sputtered from polycrystalline ceramic LSCO targets at 600 °C substrate temperature (700 °C in the case of x = 0), 45-65 W of DC power, and 1.5 Torr O2 pressure, after which the films were cooled to room temperature in 600 Torr O2 pressure. BM SCO films were grown at a substrate temperature of 700 °C using 40 W of DC power and cooled to room temperature at the growth pressure of 1.5 Torr O2. The resulting LSCO films ranged from 12-22 nm in thickness acr...,