Step nanobar Polytetrafluoroethylene OpticalElement SrTiO3 Foil Graphene Gong FrictionalForce Piezo SICM Annealed vertical_PFM Platinum PiezoelectricForceMicroscopy Galfenol ForceVolume Magnetic Force Microscopy Film Led Sphere kelvin probe force microscopy InorganicCompound CalciumHydroxyapatite AnodizedAluminumOxide Polypropylene Tungsten_disulfide AM_KPFM Ferroelectric WS2 GranadaUniv Device DomainSwitching TemperatureControllerStage MonoLayer