title: Quantitatively probing the magnetic behavior of individual nanoparticles by an AC field-modulated magnetic force microscopy.
abstract: Despite decades of advances in magnetic imaging, obtaining direct, quantitative information with nanometer scale spatial resolution remains an outstanding challenge. Current approaches, for example, Hall micromagnetometer and nitrogen-vacancy magnetometer, are limited by highly complex experimental apparatus and a dedicated sample preparation process. Here we present a new AC field-modulated magnetic force microscopy (MFM) and report the local and quantitative measurements of the magnetic information of individual magnetic nanoparticles (MNPs), which is one of the most iconic objects of nanomagnetism. This technique provides simultaneously a direct visualization of the magnetization process of the individual MNPs, with spatial resolution and magnetic sensitivity of about 4.8 nm and 1.85 × 10(-20) A m(2), respectively, enabling us to separately estimate the distributions of the dipolar fields and the local switching fields of individual MNPs. Moreover, we demonstrate that quantitative magnetization moment of individual MNPs can be routinely obtained using MFM signals. Therefore, it underscores the power of the AC field-modulated MFM for biological and biomedical applications of MNPs and opens up the possibility for directly and quantitatively probing the weak magnetic stray fields from nanoscale magnetic systems with superior spatial resolution.
authors.affiliation: School of Materials Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China.
authors.forename: Xiang
authors.initials: X
authors.lastname: Li
authors.affiliation: School of Materials Science and Engineering, Tongji University, Shanghai 201804, China.|Research Center for Engineering Science, Graduate School of Engineering &Resource Science, Akita University, Akita 010-8502, Japan.
authors.forename: Wei
authors.initials: W
authors.lastname: Lu
authors.affiliation: School of Materials Science and Engineering, Tongji University, Shanghai 201804, China.
authors.forename: Yiming
authors.initials: Y
authors.lastname: Song
authors.affiliation: School of Materials Science and Engineering, Tongji University, Shanghai 201804, China.
authors.forename: Yuxin
authors.initials: Y
authors.lastname: Wang
authors.affiliation: School of Materials Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China.
authors.forename: Aiying
authors.initials: A
authors.lastname: Chen
authors.affiliation: School of Materials Science and Engineering, Tongji University, Shanghai 201804, China.
authors.forename: Biao
authors.initials: B
authors.lastname: Yan
authors.affiliation: Research Center for Engineering Science, Graduate School of Engineering &Resource Science, Akita University, Akita 010-8502, Japan.
authors.forename: Satoru
authors.initials: S
authors.lastname: Yoshimura
authors.affiliation: Research Center for Engineering Science, Graduate School of Engineering &Resource Science, Akita University, Akita 010-8502, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Saito