title: Removal of electrostatic artifacts in magnetic force microscopy by controlled magnetization of the tip: application to superparamagnetic nanoparticles.
abstract: Magnetic force microscopy (MFM) has been demonstrated as valuable technique for the characterization of magnetic nanomaterials. To be analyzed by MFM techniques, nanomaterials are generally deposited on flat substrates, resulting in an additional contrast in MFM images due to unavoidable heterogeneous electrostatic tip-sample interactions, which cannot be easily distinguished from the magnetic one. In order to correctly interpret MFM data, a method to remove the electrostatic contributions from MFM images is needed. In this work, we propose a new MFM technique, called controlled magnetization MFM (CM-MFM), based on the in situ control of the probe magnetization state, which allows the evaluation and the elimination of electrostatic contribution in MFM images. The effectiveness of the technique is demonstrated through a challenging case study, i.e., the analysis of superparamagnetic nanoparticles in absence of applied external magnetic field. Our CM-MFM technique allowed us to acquire magnetic images depurated of the electrostatic contributions, which revealed that the magnetic field generated by the tip is sufficient to completely orient the superparamagnetic nanoparticles and that the magnetic tip-sample interaction is describable through simple models once the electrostatic artifacts are removed.
authors.affiliation: Department of Basic and Applied Sciences for Engineering, SAPIENZA University of Rome, Via A. Scarpa 16, 00161 Rome, Italy.|Lab. for Biomaterials and Bioengineering (CRC-I), Dept. Min-Met-Materials Eng. &University Hospital Research Center, Laval University, Quebec City, Canada.
authors.forename: Livia
authors.initials: L
authors.lastname: Angeloni
authors.affiliation: Department of Basic and Applied Sciences for Engineering, SAPIENZA University of Rome, Via A. Scarpa 16, 00161 Rome, Italy.
authors.forename: Daniele
authors.initials: D
authors.lastname: Passeri
authors.affiliation: Department of Basic and Applied Sciences for Engineering, SAPIENZA University of Rome, Via A. Scarpa 16, 00161 Rome, Italy.
authors.forename: Melania
authors.initials: M
authors.lastname: Reggente
authors.affiliation: Lab. for Biomaterials and Bioengineering (CRC-I), Dept. Min-Met-Materials Eng. &University Hospital Research Center, Laval University, Quebec City, Canada.
authors.forename: Diego
authors.initials: D
authors.lastname: Mantovani
authors.affiliation: Department of Basic and Applied Sciences for Engineering, SAPIENZA University of Rome, Via A. Scarpa 16, 00161 Rome, Italy.|Research Center for Nanotechnology applied to Engineering of SAPIENZA University of Rome (CNIS), Piazzale A. Moro 5, 00185 Rome, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Rossi