Polyvinylidene_fluoride MagneticForceMicroscopy Ucl hetero_structure VortexCore Tungsten MagneticPhase Carbon temperature controller AFM PVA PiezoelectricForceMicroscopy SurfaceOxidation EFMAmplitude Tin disulfide Sadowski FrictionalForceMicroscopy PolyimideFilm vertical_PFM STO India fluoroaalkane molecule mechanical_property norganic TemperatureControl Techcomp PetruPoni_Institute contact SiliconCrystal aluminum_nitride Electical&Electronics SKPM ElectroDeposition ring shape StrontiumTitanate