Fig. 2. FIB/SEM images of the notch milling workflow.

After trench-milling a (green arrow), the resulting slab is coarsely milled down to <10 µm thick b (green arrow). An initial, incomplete notch design is milled into one side of the slab, with a segment still connected b (orange arrow). This connection is then broken by milling, revealing a tab within a notch c, d (orange arrow). The lamella is then milled and polished as usual e (green arrow). A second example of a completed lamella with a notch mill is presented in f. To allow for freedom of movement (see Supplementary Fig. 8 and Supplementary Movie 9), each notch mill should separate the tab from the slab by 200+ nm. with similar results.