Magnetic force fields of isolated small nanoparticle clusters

Abstract

The usage of magnetic nanoparticles (NPs) in applications necessitates a precise mastering of their properties at the single nanoparticle level.

Dynamics of interacting magnetic nanoparticles: effective behavior from competition between Brownian and Néel relaxation

“…4). For small enough w L , this increase of t is well described by the mean-field result (23). For smaller f corresponding to larger dipolar interaction strength l, the data start to diverge earlier from the mean-field result.…”

“…is not as accurate as the one for t short , but provides a good description for weak and moderate interaction strengths. Eqn (23) holds for w L o 3 and (w L À 1)t B o t N and we have defined…”

“…However, since the magnetic properties of interacting MNPs are much less understood, [23][24][25] we here address the question about the validity and form of eqn (1) for interacting MNPs. In ref.…”

Imaging Large Iron-Oxide Nanoparticle Clusters by Field-Dependent Magnetic Force Microscopy

“…(62) Nevertheless, MFM has also the potential to qualitatively investigate the magnetization state of clusters made of several NPs, in addition to their morphology, size characteristics, and separation. (63,64) Moreover, in some cases, the magnetic interaction forces measured by the microscope can also be used for quantitative magnetization studies under magnetic fields. (65,66) Here, we present a MFM study on individual large iron-oxide nanoparticle clusters by operating the microscope under a variable magnetic field.…”

“…MFM on the other hand is a technique able to image individual clusters and to address their magnetization states at the nanometer scale. − This technique has been used for revealing magnetic properties of individual NPs − and of magnetically correlated grain systems . Nevertheless, MFM has also the potential to qualitatively investigate the magnetization state of clusters made of several NPs, in addition to their morphology, size characteristics, and separation. , Moreover, in some cases, the magnetic interaction forces measured by the microscope can also be used for quantitative magnetization studies under magnetic fields. , …”