kelvin probe force microscopy NeodymiumMagnets polyvinyl acetate Conducting OrganicCompound Hydroxyapatite Tin disulfide ContactModeDots SingleLayer FloppyDisk 2d_materials Device CastIron Sic Gallium Annealing Annealed CeNSE_IISc STM PolyvinylideneFluoride SiliconeOxide SFAs Molybdenum graphene_hybrid DomainSwitching Floppy Lattice CrystalGrowing Magnetic Force Microscopy LDPE AM-KPFM TemperatureControlledAFM Alkane P3HT WWafer