MagneticForceMicroscopy Leakage SetpointMode ForceMapping China HDD molecular_self_assembly NiFe TemperatureControllerAFM Austenite Gong PVA biocompatible Modulus Change MfmAmplitude SiliconCrystal OrganicCompound BaTiO3 University_of_Regensburg Iron INSP CNT Cobalt single_layer EFMAmplitude Resistance Electrical&Electronics SiliconeOxide Multiferroic_materials HydroGel mechanical_property Semiconductor Varistor tip_bias_mode