LaAlO3 tip_bias_mode HBN nanobar PVAC Chungnam_National_University Solution Leakage mechanical property Metal Vacuum Butterfly UnivMaryland LFM Ni81Fe19 UnivCollegeLondon temperature_control Fendb Polyurethane dielectric_trench Vanadate #EC Yeditepe_University MoS2 Strontium molecular_self_assembly dielectric trench CaMnO3 Magnetic Force Microscopy Phosphide Tungsten KelvinProbeForceMicroscopy Hole ForceVolumeImage BiasMode