Terrace thermal_property alkanes FloppyDisk Force-distance Reduction UnivCollegeLondon AlkaneFilm norganic Korea SICM LiftMode EFM Yeditepe SKPM Stiffness NUS_NNI_Nanocore bias_mode Vinylpyridine Glass LMF Permalloy Non-ContactMode Potential Ni81Fe19 Mapping Current Inorganic_Compound Alloy Pinpoint PFM OrganicSemiconductor Oxide VerticalPFM PvdfFilm temperature controller AFM