FFM Calcium FrictionalForceMicroscopy fluoroaalkane Wildtype Oxide VortexCore self_assembly PUR OxideLayer mono_layer exfoliate LiNbO3 Beads Biofilm domain_switching CP-AFM Tungsten Neodymium Piranha plastic LiIonBattery MagneticArray PetruPoni BiasMode IISCBangalore Magnetic Force Microscopy PVA PFM STM mfm_amplitude IcelandSpar NCM Chloroform Vac