LDPE H-BN alkanes Anneal SICM solar_cell C_AFM Insulator ElectrostaticForceMicroscopy Polytetrafluoroethylene dichalcogenide Calcite Iron MagneticArray Resistance Perovskite HBN AtomicSteps BiasMode exfoliate flakes contact Neodymium TemperatureControl Christmas light_emission phase_change Piezoresponse HexagonalBoronNitride FM_SKPM CP-AFM Device Water ring shape EFMAmplitude