Reversible contrast in focus series of annular bright field images of a crystalline LiMn2O4 nanowire

►Focus series of annular bright field images were observed for very thin LiMn2O4. ► Dark dips at the atomic column positions reversed to bright peaks by defocus change. ► The optimum defocus was 2nm over-focus with a convergent semi-angle of 30mrad. ► The experimental results were interpreted based on weak-phase-object approximation.