Fig. 1: Freestanding LaMnO₃ film and its lattice dynamics measured by MeV-UED.

a Top: Schematic of the freestanding LMO film achieved by removing the SAO buffer layer grown on the STO substrate. Bottom: Optical microscopy image of the LMO film on the copper mesh grid for UED experiments. The scale bar is 100 µm. b Schematic of orthorhombic structure of LaMnO₃. c The experimental [001] UED pattern obtained before photoexcitation from the freestanding LaMnO₃ film. The transmitted beam was not included to avoid saturation of the detector. The bright spots marked as (h k 0) with (h, k) being (even, even), (odd, even), (even, odd), and (odd, odd) correspond to the Bragg reflections and superlattice reflections from the a⁺b⁻c⁻, a⁻b⁺c⁻, and a⁻b⁻c⁺ twin variants, respectively. The (−880) and (880) spots are magnified showing their elliptical shape along the [110]^* and [−110]^* direction, respectively. d Simulated UED pattern based on the Bloch-wave method with the twin variants, showing good agreement with the experiment.