For AFM nanoindentation experiments, the atomic force microscope NanoWizard 4 from JPK instruments (Germany) was used. Measurements were performed in contact mode using NSC 15 cantilevers, purchased from Mikromasch, with a nominal spring constant of 40 N/m and resonance frequency of 325 kHz, and a silicon tip with a radius of 8 nm, full tip cone angle of 40°, and tip height 12-18 μm (manufacturer's data). The employed cantilevers were calibrated using the contact-free method.