The milling process consisted of four steps: trenching, rough milling, fine milling, and polishing. Trenching was performed with a 1nA beam current over an area of about 10 µm, extending approximately 10 µm above and below the desired lamellae position. The trenching stage concluded when a lamella of around 5 µm thickness was obtained. Rough milling followed, using a 300pA current, to reduce the lamella to a thickness of 1 µm and its width to around 9 µm. During the fine milling stage, a 100pA current was employed to bring the lamella down to a final thickness of 400-500 nm and a width of approximately 8 µm. Lastly, polishing was done at a 30pA milling current until the lamella was between 150-200 nm thick and 5-7 µm wide. This procedure was implemented on five selected sites on the grid using a 30kV accelerating voltage and gallium ions as the liquid metal source. The milled crystalline lamellae were subsequently stored in liquid nitrogen until the MicroED experiments in the cryo-TEM.