UC Berkeley

Bismuth ferrite has garnered considerable attention as a promising candidate for magnetoelectric spin-orbit coupled logic-in-memory. As model systems, epitaxial BiFeO₃ thin films have typically been deposited at relatively high temperatures (650-800 °C), higher than allowed for direct integration with silicon-CMOS platforms. Here, we circumvent this problem by growing lanthanum-substituted BiFeO₃ at 450 °C (which is reasonably compatible with silicon-CMOS integration) on epitaxial BaPb_0.75Bi_0.25O₃ electrodes. Notwithstanding the large lattice mismatch between the La-BiFeO₃, BaPb_0.75Bi_0.25O₃, and SrTiO₃ (001) substrates, all the layers in the heterostructures are well ordered with a [001] texture. Polarization mapping using atomic resolution STEM imaging and vector mapping established the short-range polarization ordering in the low temperature grown La-BiFeO₃. Current-voltage, pulsed-switching, fatigue, and retention measurements follow the characteristic behavior of high-temperature grown La-BiFeO₃, where SrRuO₃ typically serves as the metallic electrode. These results provide a possible route for realizing epitaxial multiferroics on complex-oxide buffer layers at low temperatures and opens the door for potential silicon-CMOS integration.