Vortex HexagonalBN BiFeO3 Fujian Platinum HanyangUniv ContactModeDot UTEM Phenanthrene Memory semifluorinated alkane SICM F14H20 Lift non_contact Domain hard_disk FAFailureAnlaysis FrictionalForce Cross-section NTU food oxide_layer DomainSwitching Magnetic Force Microscopy VortexCore CuSubstrate Sio2 Silicon Composition Growing MembraneFilter Pzt Pinpoint contact